That not recognize keyboard issue popped up for me with a reinstall of Sierra. It’s why I wish Apple still made wired keyboards.I have the Mini and the keyboard problem when I first installed was one of the most ridiculous things I have ever had to deal with in my entire history of using Apple products.
It didn't recognize my very common Logitech wireless but thankfully my daughter had a wired gaming keyboard and I was able to install with that.
After that (and specifically 11.0.1) it has been smooth sailing.
Glad you were able to get that to work.
Seeing a lot of issues I had mentioned in this thread, I’ll wait for a Mac Mini that has 32gb of RAM before trying again. I do not have the patience for early adoption though.