A) I am not convinced that success-with-complication helps if one wants heroic play. In fact, I think I still come down on the side of "it doesn't."
B) I'm also not convinced that the players need to know everything about what they're about to attempt. They should know everything their character should know, without question, but I'm not sure that's what you mean by "[having] action resolution encoded."
C) I have found that 5E has plenty of pressure points, if the players are running their characters honestly; the higher-level party I'm DMing for felt themselves to be enough in debt to an NPC that they fought a mythic (similar to stuff in the Theros book) Death Knight and some of its allies in a cage match, to save the NPC's wife's soul. (When I talk "heroic," that's what I mean.) I've also run gantlet-type adventures, and had the PCs running on fumes by the end.
I haven't run into those problems in 5E to the extent you have, which could come to differences in how we run 5E, or differences in the players. I agree, though that the PCs are extremely robust: That just means I can throw more stuff at them.
I'm not opposed to letting the PCs plan for things they know are coming. They prepped like hell (heh) for that fight against the Death Knight, and they took like a whole session prepping for the assault on Steeltear and the Masked Ones. I don't mind a PC being played as reckless, so long as it's a character thing; there are some types of characters I'd argue shouldn't/wouldn't be reckless in the ordinary course of things.
If "turtling" is an extremely cautious playstyle, where no risks are taken, I agree, and I don't encourage it in campaigns I run. I don't mind if someone chooses to optimize for AC. though, which can also be considered a form of turtling, maybe.
And I award XP for the PCs advancing story things. So, I suspect the incentives are operating a bit differently from by-the-book 5E.
So far, so good, but I haven't explicitly hacked in anything from any PbtA or FitD games, either. I haven't felt the need--I just was pointing out that playing that way works in 5E, too, because the players in the campaigns I'm running are doing exactly that--without my having posited them as the principles I want to see.
Oh, if I were going to be explicit about those principles being the ones I want in the game, I'd have to hack in stuff to make them work.
And I'm pretty sure there is a through-line in play, at least narratively, in both campaigns I'm running--though long unplanned campaigns do unquestionably have a tendency to end up kinda on the picaresque side. I'm reasonably OK with that.
A lot of stuff!
Let me work backwards (I'll probably miss stuff anyway).
1) By through-line I meant "a through line of Act Now Plan Later and Go Boldly Into Danger potently and consistently propels play from initating gamestate a all the way to endstate z." Not "a coherent through line of narrative." I'm sure your game has that!
2) By pressure points I don't mean "Story Stakes/Wins/Losses." Those are enormously important, but that isn't what I'm talking about here. Here I'm talking about (if its Dungeon World) complications/costs that feature any/all of the above:
* Oh no I've lost (disarmed or fell down a gorge) my
Spear so I don't have a weapon at all!
* Oh no I've lost my
Spear so I've lost my
Reach tag advantage!
* Oh no, I've lost my
Longknife and I'm in a deadly grapple without a
Hand tag weapon!
* Oh no, I've lost
Ammo so I can't fire my bow (or I won't be able to soon!
* Oh no, I've lost
Rations and I'm running low and we've got more Camps to make on this Journey!
* Oh no, I've lost
Adventuring Gear...how am I going to navigate this obstacle (the dark, a climb, et al)!
* Oh no, I've lost my
Bag of Books so I lose my bonus to Spout Lore!
* Oh no, my
armor/shield was damaged/ruined by the Messy tag!
* Oh no, I've got a
Debility (any of the 6 ability scores)!
* Oh no, my
Hit Points!
* Oh no, take -1 forward!
* Oh no, take -1 ongoing to a move!
* Oh no, my hireling/cohort is in trouble!
* Oh no, my Potion/Salve/Antitoxin/Bandages/Poultices is/are lost!
* Oh no, I'm
Stunned!
* Oh no,
Forceful tag is throwing me off of this cliff/into this hazard/into this bad position!
* Oh no I've lost a
Spell!
Many more than that as well. The game has dozens of Pressure Points that are extremely consequential that can be a straight up cost or an either/or decision-point for the player. 5e (and D&D broadly) just doesn't have this sort of framework of unified and diverse complications/costs that have serious teeth (both now and downstream).
3) On Action Resolution codification and table orientation (GM or player facing). I mean I guess a part of this is native to me as an athlete, outdoorsperson, and martial artist my whole life. But my experience is these sorts of people perform risk assessment and navigate obstacles in a very math-intensive way. Everything I do physically I can give you a tight percentage spread on whether I'll be able to accomplish it or not. If that is taken away from me and it becomes much more unbounded...man, I won't have any idea how to orient myself to any obstacle. If I can't orient myself to an obstacle I can't decide on an approach. If I can't decide on an approach...I can't act. If I can't act...I can't act skillfully (yes OODA Loop again!)!
Maybe I'm just a weird though (but I know there are a LOT of other people like me)!