Yup, routinely use different techniques to run Linux on my work laptop. I’ve been at places where they have official support for Linux distros, with AD integration through services like sssd. I’ve also been at places where running a virtual Linux machine was possible, others where I was allowed to unlock secure boot temporarily to be able to to add a new signed binary for a Linux distro, running on a USB stick.

I think doing just a poweroff might leave some services in an unclean state. I think systemctl poweroff make sure the services are shutdown cleanly before powering down.