But the 8069 is a microprocessor (CPU). This is a microcontroller. Radically different architecture and (typical) use case.

They don't have MMUs because they are designed to directly address a much smaller ram space. On an the micro in the article, this is only 16K. They are also designed to execute machine code directly, and automatically from an on-board or external ROM, whether a masked ROM (rare these days), an EPROM, or an EEPROM/NVRAM of various kinds. They are not designed to use an OS at all.

That's what makes this so impressive.

Trs80 Coco series used the 6809 CPU that is 16 bits. The article talks about Linux on 8 bit systems.

I'd say the Mega65 might be a good 8 bit machine to port Linux to. http://mega65.com

The 6809 was 8 bits, in the same way Z80 and 6502 and 6800 were: 8 bit data bus, 16 bit address bus.

It had a few 16 bit instructions: arithmetic on data in registers, or loading/storing a 16 bit register (8 bits at a time). I think the Z80 did as well.

Here's Wikipedia: https://en.wikipedia.org/wiki/Motorola_6809

It also had an 8x8 mul with 16 bit result.

One 16-bit feature doesn't make a CPU where every other feature is 8-bit a 16-bit CPU.

I don't think I claimed it was a 16 bit CPU.