Parents are domain names you do not include schema or path data.
So your parent should be just localhost in this example.
Sounds like you might want to try the elctron embed method instead and see if that works for you if the published iOS methods do not.
Thats if you can modify the other call data.
Bluelava devised a working iOS solution
You can always open a feature request via UserVoice instead:
https://twitch.uservoice.com/forums/310213-developers
I’m not sure if Twitch will go for it, as then that means Twitch would be maintaining an “allowlisted” list of supported frameworks. And there’ll always be “another framework” missing from the list