How to activate my iPhone with a broken home button
Solution 1:
Get the phone fixed, or buy a new one.
Solution 2:
Copied from an answer found on iFixit, this helped me set up an iPhone with a broken Home button, on iOS 14.2.
Turn off the iPhone with power button + slider, do not reboot it. Turn on again with power button and you should be able to use touch and go through settings without the need to press home button.
You can then unlock sim, activate iPhone and re-enable Assistive Touch or restore a backup.
Solution 3:
Got this issue yesterday and didn't find any solution on internet but here it is !
Using iMazing you can get around the home button press on iOS 14.
You select your device in it -> Options -> Device Settings -> Set Language & Region and voila.
You can also enable VoiceOver and follow Mike Hardy if it doesn't work for you.
You may have to reboot the phone.