Proton Pass is an open source, end-to-end encrypted password manager app. Create and store passwords, email aliases, 2FA codes, and notes on all your devices
As discussed in the January update, Android will require more work as we are rewriting more of the application, with a big focus on performance and stability. This means some Android features you have requested for Mail are not in our immediate scope for delivery. In particular, conversation view (also known as threading view) won’t make it into the first version of the new Android app, but we hope to deliver it soon after release.
It’s missing so much that iOS has. They’ve said they are releasing a rewritten app, but keep delaying it.
For example, there’s no threaded email support on Android.
https://proton.me/blog/2022-roadmap