@liaizon @fediverse In a way, this issue lies on browsers lacking decent support for custom-schemes, stuff like handling multiple handlers and ability to know if the scheme is registered at all (so a fallback can be presented instead).
Heck, it's even something that Mozilla was aware all the way back to 2010 and with the early Fediverse (OStatus) in mind. https://blog.mozilla.org/webdev/2010/07/26/registerprotocolhandler-enhancing-the-federated-web/