Well it seams like when PowerApps was created as the new custom form for SharePoint somehow the ability to have fill in options for Choice fields was forgotten.
I see there are requests people have entered for This option but I don't know that anyone created an "New Idea" for it since that was requested even yesterday.
To me this is a show stopper for a number of forms I am creating for SharePoint. I really hope this can be implemented soon.
Was anyone able to get this working and save to the SharePoint list when the SharePoint list doesn't have a toggle for "Allow Fill-in choices"?