For Homey, Just invite the new owner to your Homey like any other family member.
Then change the new user to manager from the settings- family.
Before or After transfering Homey to the new owner activate the new internet by roll over Homey and use the standard documented recovery procedure to connect to the new wifi network. Just be sure to keep all settings.
Dont forget to change the other devices and your PI to the new wifi network. And update the settings or IP address in the app connection.
Or let them create a wifi network with the same SSID and password (pre shared key) as yours but that is less secure for them as you still know that password.
