I've always been obsessed with true P2P WebRTC with QR codes but, at least back in the day, Firefox fails the offer under a very short timeout (~5 secs IIRC) which made out of band signaling completely impossible.

I have done this a couple of weeks ago on firefox and it worked fine even with a 1 minute delay. An even easier way to share the SDP offer, at laest when the clients are in physical proximity, is using a data over sound library like ggwave.

We've circled back to dial-up modems :D