I want to allow the user to add drivers to his app, because I cannot legally ship them in the snap. Can I use a shared folder of some sort and have the user copy the libs there?
a snap has two places it can write to by default, these are exposed via environment variables:
SNAP_USER_DATA -> points to:
~/snap/<snapname>/current/ and is user writable
SNAP_DATA -> points to:
/var/snap/<snapname>/current/ and is root writable
one limitation here is that daemon snaps can only access the latter (they run as root inside the sandbox and SNAP_USER_DATA would thus point to /root/snap/…)