[leni536]

Last I checked, you can't do that on more recent models, can you?

[floatboth]

You can, why would that be the case?

MrChromebox currently publishes only RW_LEGACY firmware (not full ROM, only replacing the stock SeaBIOS) for AMD Picasso/Dali and Intel Tiger Lake devices, but a) that's enough to boot whatever you want and b) you can build your own full ROM.