Right. That's why I said you'd have to have a relay just for it or use blossom. Blossom makes way more sense.

I just forked a blossom server and added a whole frontend. I think I can pretty easily add a link from .excalidraw files that just opens excalidraw with that data loaded. Work in progress, a lot of stuff is broken so I haven't shared yet:

Gallery - Blossom Gallery

The blossom parts all work because they did before I forked it. I just added the frontend. Before it was just a blossom server.