If you have not yet disconnected and packed up the unit, be aware that you can use a Windows, Mac or Linux PC to connect Rachio to your Wi-Fi. See
Other possibilities include using an old phone (even if it doesn’t have a SIM card) or a tablet to establish the initial connection.
Or, you may have a kid, parent or friend with a compatible phone that can be used for initial setup. Once connected, Rachio will update itself and will then work fine with iOS 14.2 or newer.
A “forklift upgrade” should be a last resort.