Interface for mounts outside /mnt & /media?

I have an issue with Ferdium (1) as a snap version: I cannot upload content or save files to my usual drive.

I dualboot Ubuntu & Windows, automounting the Windows drive under /files (I added an entry in fstab). I adjusted .config/user-dirs.dirs to point my user’s special folders to the Windows one. (As per a HowTo guide (2).)

The Ferdium snap doesn’t recognise these adapted user folder paths. I could work around that, if it weren’t for the fact that the snap doesn’t have access to my mounted drive at all, because it is not in the remit of the the removable-media interface (3) – which covers only /media, /run/media and /mnt. (Which I figured out via an AskUbuntu question (4).)

However, aren’t these folders intended for temporary mounts (as noted on Linux SE)? Would it make sense to allow snaps to attach to other interfaces (or recognise the user folders identified by the host)?

(Note: I’m a noob when it comes to snaps, just an end-user with a practical problem.)

Links that I couldn’t put as new user:

  1. ferdium_org
  2. howtogeek_com/howto/35807/how-to-harmonize-your-dual-boot-setup-for-windows-and-ubuntu
  3. forum_snapcraft_io/t/the-removable-media-interface/7910
  4. askubuntu_com/questions/964377/snap-application-doesnt-see-files-from-another-partition