There is a way without Google Play outlined here: https://support.symfonium.app/t/how-can-i-pay-for-symfonium-without-google-play/1290/2

I haven’t used it myself, but I’ve heard of ErsatzTV. Their docs note configuring Jellyfin as client.

https://ersatztv.org/docs/intro

I suggest Vikunja. There isn’t a mobile app to my knowledge, but the web UI on mobile and desktop is very responsive. It should cover the rest of the items on your list