U-Boot with direct NVMe boot support for eMMC/SPI Flash

[Arwen]

...
Am I going about this all wrong? I've seen other discussions that talk about skipping messing with the SPI and just make the eMMC your /boot and put the rest of root (more or less) mounted on the NVME - is that good enough?
...

It is much simpler to use the eMMC as the initial boot device, than mess with the SPI. That might change a year from now.

And yes, you can have "/boot" on the eMMC, along with U-Boot. Then use the NVMe for everything else. It won't cost you much extra in boot time. But the reduction in problems could be dramatic.