GRJ: You're a trail-blazer for sure!
When my Mother was still with us, I rigged a wireless (key fob) remote for her to use to turn on lights in the living room and to activate some buzzers in other parts of the house. They worked well throughout their usefulness. They were similar to the units that you have mentioned in that they could learn the codes so that additional remotes could be utilized.
These units look to be the right size for what you may have planned. Good find!
-- Leo