I'm using the nextcloud app on my android, and for my Linux systems I mount WebDAV using rclone, with VFS cache mode set to FULL. This way I can: 1. Have the file structure etc synced to local without downloading the files 2. Have it fetch files automatically when I try to read them. Also supports range requests, so if I want to play a video, it sort of streams it, no need to wait for download. 3. If a file has been accessed locally, it's going to be cached for a while, so even if I'm offline, I can still access the cached version without having to verify that it's the latest. If I'm online, then it will verify if it's the latest version.

Overall, this has worked great for me, but it did take me a while before I set it up correctly. Now I have a cache of files I use, and the rest of the stuff that I just keep there for backup or hogging purposes doesn't take disk space and stays in the cloud until I sync it.