Does the Mysql install location affect write speeds?
As a comparison, I uninstalled the Mysql 8.0 server, and replaced it with a 5.7 64-bit version, with the same setup: Server binaries on the regular hard drive, data files on the SSD. The speed went back to 8-10 minutes to import the SQL files.

I can only assume that the issue is with the v8.0 server, but I cannot speculate as to why. Since I have no particular reason to need the v8.0, I will stay with the v5.7 for now.