Resolved! I was fiddling around after following some online tips that hadn't worked. However, I did read a tip to first pair the mouse that had previously been used with the same keyboard. Then I replaced the keyboard batteries, turned the keyboard on, choose keyboard in the MacBook Pro system settings where I selected an option in the keyboard description to pair a new keyboard. I then went to bluetooth, held down the option+command keys, and voila, the keyboard icon appeared in the available pairing list for the first time (after previous numerous tries). I hovered over the keyboard icon until the connect button appeared, clicked and was connected to my MacBook Pro M1. What a relief! This will enable me put my MacBook on a stand and get rid of the kink in my neck.