Test version of u-boot for installation in SPI with support for starting from USB. I checked it on my model. u-boot sees all devices (USB SD eMMC NVMe) and polls them sequentially for startup. The only problem is that I can’t check for a full run with NVMe yet, u-boot sees NVMe and can read small files from It, but when I try to read the kernel, I get a read error indicating the cluster. I think this is the problem of my NVMe (for the test, I connected the simplest NVMe module). But there may not be enough additional settings in the DTB (I don’t have time to check with another module yet). Start with the rest of the media works without problems.