Merchant for missable items

It would be incredibly helpful if a merchant was added that actually sells missable items, such as Shadow Dragon/Antivan Crow faction shop items as well as loot from areas you can't return to.

I'm personally sitting at 100 hours on my first playthrough, nearing the ending. I went in blind, and am still avoiding spoilers, but I have tried looking up multiple times if there's a vendor that sells those types of things, and all I get are people saying either the crossroads wisps, or the black emporium, neither of which have the majority of the missable items. I had hoped maybe once I reached maximum faction strength the wisp shop would update and expand, but that's not the case. I also saw one person say there's a vendor that appears at the very end that has everything missable, but I doubt that's true, if it is I'll delete this. I'm just not looking forward to having to grind early game in future playthroughs just to level up and buy out one of the two faction shops as well as the other vendors that also disappear, or having to stop and look at guides to make sure I don't miss a chest while going through areas I can't return to so I don't accidentally get locked out of legendary gear because I missed a ladder or breakable wall while on a quest that has a sense of urgency (too late to even do that this playthough). The problems I have with the story and lore aspects already make me wary of replaying the game, so quality of life patches would significantly help in my opinion. On that note, I also very much agree/support with other's suggestions for a golden nug, non-faction merchant icons on the map, more companion/romance interactions, and additional character slots.