How to set up a backup server for box making machine mysql database?

Hey,

if I understood you correctly, you want a VM(or container) running a database that is reachable from the internet, right? If that is the case just create a VM(or container), load it with basically any linux distro and install MySQL, for copying the data over you can take a look at [1].

[1] https://dev.mysql.com/doc/refman/9.1/en/copying-databases.html