The older RK3399 boards are basically mainlined. The PinePhone Pro uses a variant of that SoC, the RK3399S. But it's an older SoC these days. The open source Panfrost GPU drivers for that are great though: full desktop OpenGL support! Not just that OpenGLES stuff.

Pine64 does have a newer QuartzPro64 that they're also working on mainline support for. The Orange Pi 5 uses the same SoC. And yeah support isn't there yet, but I'm hopeful: https://wiki.pine64.org/wiki/QuartzPro64_Development#Upstrea...