I had not heard of ubicloud, that's pretty cool! Thanks for the tip!

And sure:

I don't self host it, I got managed owncloud space from a domain and web host provider.

I manage my own VPS that I got from them but the cloudspace came extra with buying the domain + email services (I've managed email server at my job and no way in hell will I do that for myself, too much headache).

So basically, in short, I have a managed email + owncloud space (just 5gb, don't honestly need more) from a commercial provider and just use owncloud app on my phone and PC to sync folders on both. I keep my encrypted joplin notes and (encrypted by default) keepass database on this cloud. Owncloud takes care of syncing and I just use Joplin and KeePass on both devices and set them to use the files in owncloud folder. Never had an issue in 2 years with anything.

Technically my provider could scan my stuff, but they won't get anything out of joplin notes or keepass.

Your idea for a setup sounds way more private, but i think for my usecase I've been happy since it's so low effort and still does what I want it to do.

I have seen on lemmy people recommend syncthing (https://syncthing.net/) for keepass, which directly synchronizes a folder between devices without a middleman if you wanr. But everytime you want to sync you need to have both devices on for that as there is no automatic middleman that is always available. Maybe that could be done with a raspberry pi?

Anyway: you can easily set this up with proton if you already have proton cloud no?