Do I need to enable Secure Boot after moving to Linux?

You don't have to enable it just to use Linux. Secure Boot checks boot components against trusted signatures, so it can add protection against unauthorized changes to the boot process. Whether that's worth setting up depends on your security needs.

With it disabled, there's no Secure Boot certificate setup you need to do. You can leave things as they are if everything is working.

If you want to enable it, check your distribution's Secure Boot instructions first. Support varies, and you'll want to know whether its bootloader and kernel are signed in a way your firmware trusts before changing the setting.

Secure Boot is usually enabled in the firmware settings. Check the status again with sudo mokutil --sb-state after booting Linux.

Don't confuse the status check with a requirement to enroll a MOK. That command reports the Secure Boot state. A Machine Owner Key is a separate mechanism that can be used to trust additional signatures.

For example, an out-of-tree driver such as an Nvidia driver may need its kernel module signed with an enrolled key when Secure Boot is on. Some distributions guide you through that setup. You don't automatically need a MOK if your existing boot components and drivers are already trusted.

As for the certificates you may have heard about, their status can't be determined from that disabled result alone. Your firmware might already have updated certificates from before the switch, but check its trusted keys separately if you're planning to enable Secure Boot.