I am not sure I understood. I have a Nextcloud client and sync to a server I dont trust. Or that I dont want to encrypt with LUKS.

And I want to open decrypted tiles, use them and save them encrypted to a directory that I sync with Nextcloud.

Wooow that looks awesome!

I read about dyne, pretty cool group.

I use Nextcloud and may use other solutions too.

All the rest is with syncthing between trusted devices

Does that work with Nextcloud too? So send the encrypted stuff to Nextcloud or copy to another dir at least?

Cool! That sounds like a great option.

This would only work on single files or archives, but yes probably a good idea. I think cryptomator slices up files into equal pieces and then encrypts both, protecting against analysis of file types, but being sync-friendly.

It needs to be repeatable easily and easy to use for sync. This method would always encrypt everything new.