Can we count the Werden B115 and P127? There's only 1 115 in existence and to my knowledge all (?3?) P127's live in Ohio. While they are similar to the Banshee and Penetrator they were produced by Werden instead of ACA (similar to Darley and Federal Signal)
Also Custer Electric sirens are far and few but still in production on an as ordered basis.
Also Sparton is a company whose sirens I've seen on youtube but no one seems to acknowledge. (Models 37&38) those also seem exclusive to Ohio.