Every FR overall setting book usually has had pretty decent coverage for the region. Which is why 5e has been so frustrating for those who like the area...
Frog God Games has so many great options within their lost lands setting.
Huge sandboxy mega-dungeon and surrounding wilderness areas: Rappan Athuk
Massive Kitchen-Sink Fantasy City: Bards Gate
Dark, Gritty, horrific Rennaisance city and environs: The Blight
Norse-inspired area? Northlands Saga
Age of Sails piracy type game: Razor Coast
Boardlands gives you a variety of regions to explore
The Recently Released Grand Duchy of Ream details a specific, ancient, grasslands-culture kindom
I know you were not interested in the world setting but The Lost Lands source book is available via the World Anvil campaign management platform. The large, detailed world map has a layer when you can show adventures and source books that FGG has published for the area of the map you are looking at.
Okay, I put a lot of time and effort into that setting, and some of it is golden. Some of it, though, is hot garbage and I hate it with a passion. Over time, the more effort I put into it, the more the bad outweighed the good and I had to step away from it.
I will state, however, that the Quests of Doom books are bloody fantastic as filler stuff.
What have you found to be "hot garbage"? I'm not trying to bait you into an argument, you like what you like and hate what you hate. I'm just curious.
My only disappointments are generally related to the fact that in their rush to get these massive books to market, copy editing and play testing suffer. A lot of their conversions to 5e could use some work. I've also found errors and omissions in their maps in Rappan Athuk and Tegel Manor.
Regardless of what one things of the Lost Lands setting, what they are doing with it and World Anvil is very very cool. I hope it proves successful and prompts WotC, Paizo, Kobold Press and others to similarly create subscription models for setting material with cross-referenced, layered content.
The only thing that is missing is that World Anvil doesn't have an easy way to take content from a subscribed Realm and copy that into your own or to take a published realm and made a copy for yourself for your own campaign. I want to make use of all these cool new digital tools, but I have no interesting in making data entry a major part of my hobby. RealmWork's model was best but they were never able to monetize it. They should have went with an online, patreon/subscription model rather than a kickstarted, license-based offline software model.