I feel like Amethyst does that. If a comment note is clicked (from the Conversations feed) I'm starting in the position within entire history from original note - ending with all the comments.
Can quickly scroll up/down and return by sideway R>L swipe. Neat.
Amethyst is mobile (Android), so not sure if apply to the criteria as all examples are web/PWA.
I'm using Coracle also a lot, both PWA and mobile because of this ability to see more of the context.