You could try MCM https://www.mcminone.com/Default.asp?cookie%5Ftest=1 they have a lot of home and security video equipment
Get the catalogs theres a lot more then on the web site, plus good monthly sales.

Also this product may work for some of you, https://www.iautomate.com/h441.html
The automatic switching will be the most difficult to find


Merritt

Business Telephones & Equipment + Commercial Audio/Video Products
Commercial Communications . . . Turner, Maine
If it was built after 1980 don't expect it to work right.