Upgrading MySQL from 5.7 to 8.0

I need to upgrade one of my servers, running mysql 5.7. The DB and the OS is on different drives on my machine. Can I drop the DB's from my 5.7 installation, reinstall the server with new OS and mysql 8.0, and then after the fact just reattach the DB's? I have been running a mysqldump but it is very slow. I am a mysql n00b btw. Any advise will be appreciated. Still trying to figure out what my steps are