Which cameras support FTP upload to a gallery?
Most professional and enthusiast bodies released in the last decade support FTP or FTPS, either natively or through a wireless transmitter accessory. That covers current Canon EOS R, Nikon Z, Sony Alpha and Fujifilm X and GFX bodies. Check your manual for 'FTP transfer' or 'network settings' before buying anything extra.
How to check quickly
Search your camera's manual for FTP. If it appears under network or communication settings, you already have what you need. If it does not, an accessory transmitter usually adds it, and on some bodies a tethered phone will do the job.
FTP, FTPS and SFTP
FTPS is FTP with TLS, and it is what you want over public venue Wi-Fi. SFTP is a different protocol that runs over SSH and fewer cameras speak it. Support varies by body, so check which of the three your camera lists.
In SnapFlow
There is a per-camera compatibility list at /compatibility, and albums accept both FTP and FTPS.