I’ve been looking at getting a odroid h4 ultra as my next toy. It would suit you I think.

Take my upvote. I use owncloud, I have no need for apps on my self hosted cloud backup.

I use weather&radar by wetter online GmbH on android, it’s free version is good, but worth the upgrade to remove the adverts and increase the zoom on map. Météobleu is very nice, and has beautiful animation, but It’s not all to my tastes.

I use an oracle free tier server for my heavy lifting (wordpress and owncloud), and have a pi4 on my fibre optic connection which is my storage.