Today I began building the Guix System for my ROCKPro64. I installed Guix on top of Debian and tried to build uboot, it works:
guix build u-boot-rockpro64-rk3399 successfully built /gnu/store/g1d4kjgn9b46vqk9mwhd0kc2r6sfi7cz-u-boot- rockpro64-rk3399-2022.04.drv /gnu/store/90p0yndkj89c5chnri2asj9m46glxq50-u-boot-rockpro64-rk3399- 2022.04 Since my old Android Tablet has an Intel Atom SoC, I could easily install Debian, on top of that I installed Wesnoth, which I had packed from my Laptop running the full Guix System.