Haven't used one in years, when my last copy of the one you (are/were) using finally died. You are correct, Apple hasn't made them for close to a decade, at least the wired model. I suspect you can still find them with a search on the web.
I know you don't want to hear it, but I only use the Magic Trackpad 2, no buttons or wires, multi-pressure sensitive, multi-finger gestures. And no cat hair problems!!
It does have a battery but once a week, I plug it into a lightening cable over night. Do the same with the wireless keyboard about once a month. They will alert you if the charge is getting low. No software compatibility problems, of course.
I did keep my Magic Mouse on the desk for several months after I was given the earlier Trackpad. "Wireless" is much neater and the communications between the devices and the Mac are fine for letting me know when they need charging! The worst part is Apple's extravagant prices!
Amazon has them cheaper although they may be last years version.
EDIT: Since Amazon is now an "Authorized Dealer" they may not be able to sell anything but new stuff... As far as MS mice, I remember many Mac folk always claiming the old models were the best ones ever made.