The 2 Batteries inside the Wyze Palm Lock can they both be purchased off Amazon or somewhere else?
Welcome to the Forum, @bfpa40! 
I haven’t seen Palm Lock’s Backup Battery available as a separate item, but its Main Battery is the same Removable Battery Pack used by Battery Cam Pro and Duo Cam Doorbell, and Wyze does sell those if you find you need extras for some reason. What did Support say when you asked them?