boldsuck GNOME and ZorinOS have their rebranded Variants too, GSConnect and ZorinConnect afaik.
A tip: long press on start screen and create a widget, select "Settings". A page pops up, what widget you want, select "Devices". This way you can quickly enable or disable the different file transfer modes.
As for attack surface, afaik by default Android uses "MTP" when connected to a PC. Use the Developer Options setting you already discovered to change that to "no connection" by default. I will open an issue about including that toggle in the Security settings page.
Also, for Filesharing there are better options imho.
- KDE connect and the like: not recommended, it doesnt use systemd on Linux so you cant disable it easily. Afaik
touch ~/.config/autostart/kdeconnectd.desktop disables it from autostarting by overriding it with an empty file (for this user)
- localsend is a way better alternative for filesharing, has a flatpak with very good default permissions
- syncthing (syncthingy as flatpak) is best for regular transfers. You can disable "global discovery" to make it only work on LAN. You can even use it for sharing files between user profiles by directing it to localhost, which is the same between the profiles. (Afaik this is planned to change, so it will no longer work in some future where user profiles have their seperate localhosts)
Using some restricted setting like MIDI might reduce attack surface.
On fancy systems like QubesOS you could maybe have a dedicated container just for connecting.
Also note that on Linux without root nobody has admin privileges, if you haven't added the udev rules. If you installed adb and installed the OS you likely have, so removing the package should remove the udev rules too.