Isn’t there the option ‘Request Desktop Site’ on every major Android/iOS browser? (This should change the user agent, it isn’t persistent as your solution though)
P.S.: Tried about:config on Firefox on iOS and it didn’t work
There is, but those sites don’t care about that.
All they care about is the User Agent string.
Also request desktop might change the user agent string, but not sufficiently, it still won’t think you’re on a PC.
Haven’t tried it on iOS.