“Turns out, the difference in the socket is just a few pins here and there”
Intel said Z170 and Z270 boards stop at 7th generation chips. A few strips of Kapton tape and a BIOS mod run 8th and 9th generation Coffee Lake CPUs in the same socket. On one Asus board a single jumper wire does it. The incompatibility was a sales strategy, and BootGuard’s signed BIOS images exist to keep it that way.