Local here (didn't know Jim Lowder still lived in the area--cool!). Welcome to Milwaukee. It's got its problems like a city of any decent size does, but there's lots of good people and things to enjoy here.
FLGS: I'm honestly not very impressed with most of our local game stores (which seems like a crime, given the city's prominence in the history of the hobby), but I do patronize a number of them, and most have some kind of rewards program.
Board Game Barrister has several locations; they closed at least one during the pandemic and opened another relatively recently. Last I checked, their Bayshore store was the biggest and probably has the most play space of their stores, though you may want to visit around to confirm (their Greenfield store had what looked like a good amount of space to me). Good variety of indie RPGs. Staff tends to be friendly and knowledgeable, but I notice they charge slightly over SRP on a lot/most/all of their product, which I haven't had the guts to ask an employee about.
TK Games would be a bit of a schlep from your location to Menomonee Falls. It's run by a husband and wife team who are always friendly with me. I don't get in there much anymore since 1.) they recently moved into a MUCH smaller space in the same strip mall and it... really doesn't work for a game store ; 2.) They've progressively gotten more "all-in" on Magic and 99% of the limited shelf space is taken up by board games, so the RPGs are in one sad case near the door; and 3.) They often don't get in new RPG stuff right away, and even big-ticket D&D books arrive late or not at all. I try to give them business because I like them, but these things have made it hard.
Gamers Realm I haven't been to since they switched locations some years ago (back when they were "Realm of the Dragon"). I liked them well enough, though that space and layout were terrible for that kind of use, so I imagine the current location is an improvement.
Pink Bunny, as far as I know, is just a storefront selling CCGs, so I think your instinct is right on that one.
Game Universe (three locations) is the one I tend to try first, though I have some issues with them, too. If you're looking for play space, their flagship store in Franklin has the most (I haven't been to the new store in Mequon, so I can't vouch for it). Good variety of stuff. I've dealt with some truly horrendous staff there over the years, but the last couple of years they seem to have stabilized. It doesn't hurt that one of the current store managers is a friendly acquaintance from our early AL days (tell Darlene I said Hi... wait, you don't know my name, never mind). RPGs are, of course, third place after Magic and board games, but they do maintain a good selection. If you go to Franklin, try the Chinese buffet at the other end of the strip mall.
The Warhammer store (I assume the one in Greenfield is the only one) struck me as kind of sparse with bad hours, but the owner/operator was clearly a smart dude passionate about his hobby/business, so it should suit your needs if you're really into that corner of the hobby. It's a stone's throw from one of the Board Game Barrister locations, too, so you could check out both at the same time. Grab a cheeseburger with the works at Kopp's while you're over there.
Their gaming presence is minimal, but, as Mr. Lowder suggests, if you want comic books and anime, Lost World of Wonders is indeed a nice space with a lot of variety of stock (I was a longtime employee of one of their competitors, so I won't heap
too much praise on them, but it's a generally well-run store).
I'm not familiar with the others you mention in your post, but if you're willing to drive, I've heard good things about The Sanctum (in Racine). It would be a field trip for you, but Noble Knight in Madison is WELL worth visiting; I've gotten in the habit of placing a big online order and picking it up while I'm in town for Gamehole Con. They are also my go-to for Free RPG Day, since the Milwaukee stores tend to to be EXTREMELY blase about it, if they even participate at all.
CONVENTIONS: Midwinter Gaming Convention happens every January. They recently switched venues from downtown to the 'burbs (closer to where I live). It's very LARP heavy (which was its original purpose), but does have some board and roleplaying games. I haven't attended since pre-pandemic, so I don't know what it's like or what the attendance is these days.
If you're on Facebook (I am not), you might want to look up Cold Iron Conventions. They run very bare-bones conventions (i.e. 99% D&D Adventurers League games in hotel basement ballrooms), but they've been going for decades now and are fine if you want some no-frills convention gaming. They run several each year in SE Wisconsin and northern Illinois.
I don't know if Nexus Game Fair is still going, but I found it to be not very well organized and stopped attending when I noticed it declining year to year. (Actually, looking it up now, they appear to have let the domain name lapse and the Facebook page hasn't been updated since 2022).
My two favorite cons are Gamehole Con (Madison) and Gary Con (Lake Geneva). Both easily driveable from Milwaukee and mid-sized cons with very different flavors and their own pros and cons (no pun intended). I do a lot of AL (probably with or within a few feet of
@darjr and
@billd91) and find these are both good cons with enthusiastic people. Gary Con is coming up in March and Gamehole (bad name, good convention) is in October. Again, unfortunately because of the city's history with the hobby, it's a shame Milwaukee proper doesn't have anything comparable to these.
If you check out tabletop.events and warhorn.net, there are any number of smaller cons around, though I'm still not sure what these are like post-pandemic. There's a small charity con in Illinois called the d8 Summit that I've liked (tell Connor I said Hi... no, wait, you still don't know my name, never mind).
LFG: There is a Discord for Milwaukee TTRPG players, but I unfortunately haven't been on it in years, so I can't send you an invite. You might want to see which stores are doing Adventurers League and make friends that way; that's how I met most of my current group. (That and conventions--you eventually see the same faces over and over again, but in Minnesota you probably had that, too.)
I stopped using Meetup when they wanted to charge us to use it, so I can't help you there, but I did get in some games that way (again, pre-pandemic).
OTHER: At one point there were at least 3-4 different gaming bars in the city, though now I think that number's dwindled. 42 Lounge (downtown) has closed and one that really should have worked, the gaming bar run by the Board Game Barrister on Milwaukee's bustling East Side, was another pandemic casualty. Binary, now "Nicky Migz," in West Allis, has switched ownership several times and is just about done phasing out the gaming angle; the last time I played there, they had moved all the board games to the basement and funneled the gamers down there to play. The last one standing might be Faklandia Brewing in St. Francis, which has a dedicated gaming space (frequently taken by esports), though we've played plenty of times in the restaurant itself. Decent food, average microbrews. I like it, though it's well out of my way. You mention a few more that I haven't heard of and should probably check out. There's no reason a city with as many gamers as Milwaukee couldn't sustain at least a couple of gaming bars.
That... turned out longer than I expected, but hopefully that gives you something to chew on. I encourage you to take my opinions for what they're worth and check out all these places on your own to see what feels right.
