If you're interested in monetizing this:
I would pay a fee for this - say $4/month. The only features I would like at this price:
1. Authentication (-H "Authorization: Bearer <token>" would be good enough) - at the level of the routes. This sounds like what you have done for routes like '/' anyway.
2. A CLI to tell which routes I "own".
3. Persistence of messages on the patchbay server up to some reasonable time limit T so that consumers can replay messages since time T without the publishers being blocked on their side.
I would pay $8 per month if:
1. You hosted consumers (go binaries or docker containers which would accept the body and headers of the HTTP response on the consumer side and do something with it), ran them for me in a loop
2. Guaranteed me some level of isolation for things like API keys, etc. which would be passed to my consumers in some fashion.
Even if it were open source, at these prices, I would buy. Don't want the headache of hosting it myself.