USBs aren’t convenient enough. I’ve done wifi sharing via FTP, which didnt require WAN. Ftp was slow to set up. My bluetooth’s bandwidth seems very small?
A 1 click to install app across multiple devices, that only uses LAN, would be ideal. Right now, I just transfer files with element
Trebleshot between phones and phones <-> PCs.
It is on F-Droid.
Between PCs in a same network, uses Samba (some DEs allow to share folder in folder properties) or if you are in a dynamic environment (school) try KouChat which allow sharing files and not only LAN chat.