@maybenot @nixCraft I guess you're right.
Out of sheer interest I tested creation of google and instagram accounts on a clean android device, and both were successful without even providing a phone number. Same trick didn't play out through a regular desktop browser. So there is indeed difference, but the question stays, can an emulator be configured to mimic the actual device close enough?
Unfortunately, I don't have any android emulators available here, so cannot do a proper test just yet