What about oreboot, the Rust version of coreboot? I know you have a history with writing Rust code, so are you looking at oreboot as an alternative to coreboot for these purposes, as well?
I can't answer the technical side of that really well (IIRC something about targetting different things or something), but I wanted to comment that the name (Coreboot without the C) is genius. There is an Oreboot sticker on my fridge.
