There was a firmware update today that adds LAN-Only mode, which should mean that there’s now some kind of FTP connectivity to the printer (which wouldn’t be limited to LAN-Only mode BTW). I haven’t played around with it yet.
P1P and AMS Firmware Release History | Bambu Lab Wiki
EDIT: I can’t seem to connect to FTP (both with and without LAN-only mode enabled). The slicer can’t view media remotely either. Maybe they didn’t add FTP for LAN-only and are doing something else instead 
EDIT 2: We can now connect to FTP on the P1P - Bambu Lab P1P - Bambu Lab Community Forum