I believe KDE connect does this in a pretty seamless way. I normally just put the file into a “scratch” folder in my nextcloud instance - but KDE connect would probably be better from a UX perspective

Can’t recommend Pairdrop enough. And it’s open source.

syncthing is pretty great.

If you create a shared folder using your OS (which in Windows creates an SMB share) you can then use any FOSS file browser app with SMB/samba support to move files back and forth directly. Many of them support that protocol since it’s common. Amaze is one such app that I’ve used for this. You’ll need to set the shared folder to allow write privileges if you’ll be sending things from your phone, and you might want to protect it with a username/password for security.

https://snapdrop.net

https://github.com/localsend/localsend

Just found a good command line one.

https://github.com/schollz/croc

MyPhoneExplorer

Localsend works great for cross platform transfers (and works over local network, without internet)

android nearby share is great now that you can send files to and from windows (there’s even a receiver only program for mac now)

Tailscale Send?

Telegram, lol