The FSF must decide whether to endorse a product, and it must be requested by the supplier. So if a product could be endorsed, but isn't, it's either being reviewed or has not been submitted by the vendor.

In fact, I'm interested in their product commercially for Minifree, and also interested in terms of Libreboot. You can replace the default uboot firmware with coreboot, which offers many more features and there's where my company could really offer some nice custom services.

It has been on TODO for Libreboot since May 2021: https://libreboot.org/tasks/#investigate-u-boot

It is mentioned here, in the context of u-boot specifically, but I'm aware that coreboot also supports it.