The libmysql.dll from 5.7.36 64-bit (not 32-bit) did the trick for my AutoHotkey script after we upgraded to MySQL 8, thank you! (The libmysql.dll from the actual MySQL 8 64-bit .zip release didn't work...Probably due to old AHK code I'm using.) 5.7.36 seems like such a random version number when it comes to supporting MySQL 8, but who cares, I guess.
I didn't try the following, but FWIW, somebody on the AutoHotkey forums claims there's a more up-to-date 32-bit MySQL 8 libmysql.dll in the release of HeidiSQL