I had a similar idea but for wireguard only, where you would allow people to join a vpn through a "shared" jumpbox. To get started with wg is very simple, the problem is the same you need public IP address to scaffold everything.
Out of the two options I probably would prefer going wg route, just because it generalizes better. But this is a pretty cool demo of webrtc.
I think Iroh has a way of doing it using either DNS or BitTorrent DHT. Not perfect but fairly decentralized
A browser can't join a DHT though because of no UDP sockets, so the connecting side would need a native client, which is the thing bitbang avoids. And DHT lets you locate the peer, but you still need somewhere to trade SDP and ICE candidates, so the rendezvous stays either way I think.
What I can do is keep the broker small enough that self-hosting is realistic, which is where it is now -- no accounts, no registry, nothing that grants access, only a simple broker.
On generalizing: wg wins for "put these machines on one network." WebRTC wins on reach, because the connecting side can be a browser -- a phone, a borrowed laptop, a machine you don't administer -- with nothing installed. A wg jumpbox still needs a client on both ends and a public IP for the box. Different tradeoff rather than a strictly better one.