I saw that, indeed. A cursory scan gave me the impression there's nothing fundamentally new there about how to unbrick an RKnnnn device (e.g. assumes you have a Windows machine at hand).
The instructions are specifically Linux only, using upgrade_tool.
Oh, indeed, I focused on the "RKBatchTool" part and completely overlooked the "upgrade_tool" part (which is indeed new to me).
Yay! I'll get to give it another try! Thank you,
Stefan