Yup there's at least a few projects that can do in browser file transfer using WebRTC e.g.

https://sendfiles.dev/

https://sharedrop.io/

https://github.com/kern/filepizza

And of course https://github.com/magic-wormhole/magic-wormhole (they used to have a website too but maybe that went away?)

Yes, there are relays to connect the clients together and then the transfer is direct.

Several years ago when I was doing consulting I had lots of clients that blocked all the normal file sharing domains to prevent people from getting files into servers but magic wormhole always worked for me. I'd stash a wormhole-william (magic wormhole compatible Go application) executable in our installer deliverable and then I could update the software without IT's help in the future (I often had RDP access). The headaches saved by cutting red tape were worth the risk for me.

Something like this that encrypted and uploaded to IPFS would be neat.

Oh I see. syncthing is more for keeping 2 directories synched between machines. I guess in a sense, it's more of a Dropbox competitor while croc and sharr are for one-off file transfers. For awhile, I ran an owncloud server at work for internal use. It was pretty good for file synching, but required some port forwarding through the router. These solutions mentioned here seem to all have a public host somewhere to eliminate that need.