I don’t want to download anything, I want to edit in place on the network storage. I’m using my computers as much as possible with only the OS, applications, and basic user account on each machine. No content or work resides on them.
The problem is some types of file formats, like photo library databases for Aperture / Photos have to be hosted on an HFS / APFS formatted drive. I don’t want those residing on an individual Mac’s internal storage.
Now, I could keep them in sparse disk images on a BTRFS NAS, which adds a mounting step to using them, and requires a Time Machine backup, possibly hosted on the NAS itself, to provide versioned backup of those files. It also requires i set up a dedicated non-snapshot volume for them, because the Synology snapshot utility lacks the granularity of Time Machine’s exclusions list.