> Could an every day consumer buy a Sparc motherboard, chip, and build their own system? No.
Yes:
Yes:
It appears there is a Linux kernel port: https://www.gaisler.com/products/linux-for-leon
I'll give you the benefit of the doubt that you can load a Linux distro on there. You have a couple other problems: there's no ethernet or wifi, and you only have 512 megs of RAM.
"Consumers" can be running it just as much as "consumers" could be running Raspberry Pis, which could also be considered 'embedded' by some. SPARC is no less (or more) proprietary than ARM: you can license the ISA, fab a CPU, and sell some kind of hardware stack.
Do you think it would be more or less difficult to get a license from Intel/AMD for x86(_X64) than ARM and/or SPARC so you could fab your own chips?
But yes, you are correct, it's much easier to get a SPARC license.
Not someone looking for rad hardened boards with flight qualified bootloaders...