I ended up moving from Syncthing to FolderSync, the Syncthing setup for adding folders is pretty tedious and I can reuse my existing webdav (or sftp) server with FolderSync.

My use case was probably simpler than some peoples use of syncthing as I just use it for backing up photos/messages/settings and dont need it to be instant.

My only issue with FolderSync is that its proprietary but its the only option i found that worked well. The various rclone frontends that exist also didnt work nicely with the webdav server I use so I settled on it, its very polished so I dont mind too much.

For those curious: https://foldersync.io/

10 euros for an Android license for or $28 (yes they use two currencies on one page) for a desktop license. The free ad supported version on the play store has over a million downloads.

roundsync is good too