Alright! A very early version available now, mileage will probably vary, really curious if someone can get it to work and get feedback:
https://papayaphone.com/Domain name papayaphone is cool, but nothing is showing for me on that website except error message, and I tried several different browsers.
Only browser that worked for me was Tor browser, so maybe there are restrictions for some IP addresses and regions?
I also wonder if Tor browser would even work and have a good call quality, so I didn't test it yet.
I did notice that QR code was not showing up when I created invoice, that is probably something related with strict Tor browser settings, but copy invoice would work just fine.

This is error message I got in my Firefox/Librewolf browsers:

Secure Connection Failed
An error occurred during a connection to papayaphone.com. SSL received a record that exceeded the maximum permissible length.
Error code: SSL_ERROR_RX_RECORD_TOO_LONG