Looking forward to it. Getting an rk3399 device ryf-certified would be great. They have accelerated 3d graphics and video codecs that are (AFAIK) fully supported by fully free software. It would be, although not very powerful, the most modern affordable ryf-certified device available. I really hope you do it.
Also in your list of tasks you list ROCKPro64. Although I really like pine64 steps, I think the best rk3399 device for such a task is the Rock Pi 4 Model A Plus, it's got a faster processor, no wifi and the usb-c port is used for power only: no need to care about blobs for eDP! So, if you are thinking about a board to support, I'd suggest you to think about the Rock Pi 4 Model A Plus.
Also in your list of tasks you list ROCKPro64. Although I really like pine64 steps, I think the best rk3399 device for such a task is the Rock Pi 4 Model A Plus, it's got a faster processor, no wifi and the usb-c port is used for power only: no need to care about blobs for eDP! So, if you are thinking about a board to support, I'd suggest you to think about the Rock Pi 4 Model A Plus.