hi @julesinspaaace, (and thanks ogra).
For awareness, the removable-media interface is considered sensitive, which means not only does it’s use require specific permission from the reviewers team here, but also that the publisher be vetted. There are some guidelines on the process for auto-connections page (search for removable-media).
The home interface of course is auto-connected once you plug that, but typically removable-media remains a manual connection unless the criteria linked above are satisfied (I mention this especially because you mention you’re just learning how to package snaps).