I know this is a bit old, but you can onboard super easy with keychain, I did use it already.
The new user downloads keychain app and there is an option to create account with a friend. Their app will generate the keys, and will show a QR code. The onboarder scans the QR code with their keychain app and will be prompted to pay 3 Hive or use an account creation token.
The keys are already set in the new user device, they don't even have to type it in, it's ready to use. But it's a good idea to tell them to write it down somewhere later.
Super easy!