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
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=6e80df5e3344092a391468b1718e412f0dd151c1
do you have USB to UART cable?
To close out this topic (and to help those searching), support was added here, and netgear_r6900-v2-* images are available for 22.03.0-rc1.
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!