Im using this but suggestions would be helpful:

Thanks good feedback

for example the corner on the left. Buttons somehow look better. macOS gives the the feeling of sharpnes. Im so sorry its so difficult for me to discripe it.

No.

Ahh good hint. Not polished. Windows could be more beautyful for example.

In my usecase i tested unraid, ubuntu server and xpenology fits Perfekt for me for example with the photos app. I have a real small NAS DS218j running 24/7. My xpenology server runs like 4 hours oder night or automaticly longer if needed. The smaller one syncs easy to the otter ones. Also create and recover Backups is easy there.

I use xpenology. You can save money if u use that.

Can you suggest a android app for that?

This is also what i dont understand. I thought there should be a indexer but i never found one.

Are there Forums with the tenfingers URLs or how does this work?

I use yunohost for this. Ist possible there to use the sso etc. The default Installation Help to make a Quick and secure Installation.