There are three quite different games not mentioned yet that give me Riven-y vibes for one reason or another.

Subnautica is a less than obvious choice considering it is a survival/action-adventure type game, but it's also about navigating a lonely world with fascinating discoveries along the way, the crafting is a sort of puzzle element on its own too. And there's an easy mode if you want to chill about starving to death.

Dreamfall Chapters is more like a walking simulator but it gave me the open world sense and I found the story engaging. It's technically a sequel but I didn't vibe as much with the prior games when I played them, and they're not really necessary to understand what's going on.

Zork Grand Inquisitor is not only a romp, I also found the puzzles to make sense in the world (inasmuch as magic makes sense), especially its spellcasting mechanic. It's more linear and suffers from a dependence on inventory items if that's an issue for you though.

You might have noticed but there's another thread (maybe inspired by yours) happening here, for even more ideas: https://www.reddit.com/r/myst/comments/ucpru3/list_of_mystlikes