It seems that the clevo boot guard, and possibly other signing keys have been shared regularly on their official site, which should allow for coreboot/dasharo/system76 ports to work with a wider variety of their machines.
The OP in the linked thread has not fully fleshed out the process, but in theory, once you can use the keys to build an image disabling boot guard - level 0, it should in theory then leave the machine open to being reflashed, though I'm not sure how true that is.
Clevo is like the 3rd largest manufacturer, and is sold as a number of names - XMG, Asus, HP, Alienware, System76, NovaCustom, Tuxedo, Eurocom, and many more...a lot of laptops they make are just ODM badged.
