Thanks for your posts on this.
I'm a G4 owner who's being doing this until today when I foolishly updated the app following a service. I tried to connect to remove the service alert beeps but had trouble connecting to the bike, so I stupidly updated the app which is so bad. At first it saw the bike, but would not pair, now it won't even let me sign in. I've learned from this thread that even I'll be stuck in EU mode too which is a joke.
I found this method to reset the controller in EU or USA mode without the app. Does this method apply to the G4? sn4pnt1_green_resetting_controller (just noticed the date in the url ♂️)
I think I'll get connected with/without gocycle's help and then sideload the apk as you suggest.
The old app both applies updates to itself and prompts you to update the firmware to the bike seperately. I'm hoping that by reverting to an old app version I can continue to use the bike as I have done for 2 years without a 15mph limit.