No, the issue here is that the HDMI 2.1 NDA is so strict that releasing an open source implementation is forbidden no matter how much you pay them. AMD has access to the specs, they've implemented it in hardware and in their closed source Windows driver, but they're not allowed to add it to their open source Linux driver.
Nvidia does support HDMI 2.1 on Linux since their driver is closed source (but that causes its own problems). Maybe AMD could compromise by releasing a minimal binary blob which only exposes the HDMI 2.1 implementation and nothing else.
Would someone doing a clean room reverse engineering be permissible to then share would they built?
But Adafruit points out a problem, which is that the cloud service is the only available option for students using school-issued Chromebooks. I can confirm that a school-issued Chromebook is likely to be set up to lock out access to any programming tools. We wouldn't want children to learn coding after all, right?
I think relying on a corporation to preserve our freedom to code is a bit too optimistic.