Annnnnnnd with the linux payload we're back to linuxbios :-)
For a payload chooser and such I can offer two options:
1) petitboot has a boot menu type thing
2) u-root (
u-root.tk) is going to have a boot menu type thing, as we've been asked to do one.
Overall I like the idea of the linux payload, of course :-)
If you're going to do that, however, I strongly recommend going with a 16 M flash part. 8 will work for now but you're going to have issues long term. Linux is not getting smaller over time ...
I'm actually working on this now so would like to help if possible.
with linux 4, and the new kexec "just load this file and boot it please" support, it's very easy to use linux as a bootloader, far easier than it used to be. We even have a kexec command written in Go in u-root. My general experience is that linux is by far the best bootstrap out there, as its drivers tend to be much more hardened than most bootloaders.
ron