Modern Linux can't even scratch a 486 and some Motorola platforms. Or VAX. Heck, I run NetBSD 10.1 vanilla under simh 3.8 for 9front emulated on an amd64 laptop (old Celeron, 2GB). Slow, but enough to play Slashem.
On portability on compilers, plan9/9front it's unbeatable. Do you now Go compiling from any OS to any arch? The same here, but just for an OS obviously. Albeit I can still run Golang under i386, and tools like Rclone under 9front i386. That's really cool.
That's a very limited view of what portability means.
Driver support for a niche SoC? Good luck getting NetBSD on before Linux. The sheer amount of SoCs supported by the Linux kernel dwarfs anything NetBSD has to offer.
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