I'd like to add support for Netgear r6900v2. I've never done it but it should be exceptionally easy as it is stated here and here that it is functionally identical to the already supported Netgear r6700v2. I don't think it would take much, I just don't understand the developer directions for adding a device. I think its probably just not become official because of developer access so maybe I can be helpful? Or point me in the right direction for replicating this pull request and adding it myself.
start by studying the commit for the already supported one
do you have USB to UART cable?
I had flashed 21.xx to mine using the R6800 image, so to upgrade & test this, I first did a normal sysupgrade using the 22.03 R6800 image (in case some upgrade process might fail due to the changing board ID). Then I force-flashed the R6900v2 sysupgrade on top of it. No problems - working great!