It is a form of linux, it's a Xen Hypervisor running a bunch of virtual machines, it's optimized for security and privacy. I've never reccomended it, it's the most complex OS ive used with a steep learning curve and a lot of limitations.

It's been flawless for me, I have read mixed reviews online, but it hasn't been representative of my experience.

I am running three OS's on it, doing fairly heavy gaming, running dozens of VM's in QubesOS. The exchangeable ports have all worked automagically in linux.

Really the companies commitment to repairability and willingness to publish some specs to create a little ecosystem was really the most appealing part. Them introducing an upgraded mobo for the FW13 was a big milestone to me.

Lot's of companies make great laptops, many with better performance per dollar, however most of the companies are pretty irritating or despicable in some manner. I will continue to fund companies that share my values.

Purism and System76 were other brands I considered.

I'll expand it a little. System76 is a company that makes PCs with a lot of user-replaceable parts. Coreboot is the firmware on the motherboard, and it's open source instead of locked in to a manufacturer. PopOS is the operating system built by System76, based on Ubuntu, which is a common and popular Linux distribution.