How did you flash the Mint install USB? If you flashed it directly using a tool like Rufus or Balena Etcher, it should work just fine under secure boot, so you should confirm that it’s booting properly with the F3 boot menu.
In my experience, other tools like Ventoy to get multiple isos on one disk haven’t worked with secure boot.
Mint itself will also work with secure boot, although don’t try to enable hibernate, it’ll break your sleep verbs.
Be careful with codecs, I know Mint has the option to install codecs compatible with secure boot if you have it enabled when you boot the install disk. If you run into video issues that might be the culprit.