I worked for a shady evil company, and when they illegally fired me, I never ended up returning a laptop - thinkpad running windoze.
Let’s say I wanted to put Win 8 or similar on it so I can play some video games. What would potentially be barriers to doing this? Said evil company is hopefully going out of business soon, and is a clusterfuck anyway, so they might not end up asking for it back.
The main risk on company laptops is confidential data on the machine itself or any access the machine has to internal resources, so most locks are designed to be hard agaist that. The device itself tends to have more “bypassable” protection.
By which I mean: If the machine is locked down, it’s usually possible to clear and reset the lock somehow as long as you’re fine losing the data on it.
The specifics vary, but try looking up the model and instructions for resetting and wiping the BIOS/UEFI and see if that has any hurdles.