Not quite what you’re looking for, but the trunks app is pretty good. I have it set to “show context” so it shows whatever is being replied to, and you can also view multi-post threads as a single post

StrongLifts

Farscape

Before I switched to using Proton Pass I was using keepass and storing my database file on my cloud drive so that I could access it from my phone. The integration wasn’t as good as Proton Pass, but I was in full control of my passwords database.