I ended up getting an EA8100 V2 (no option to choose the version).
There is very little info on V2, but what I found was that hardware seems to be the same as V1.
Since v1 is supported, v2 has a snapshot for it and v2 is pretty much the only one still available, it would be nice to get v2 in one of the next builds.
Since I have it, I would like to help as much as I can. To preserve the warranty, I don’t want to solder any serial header to it, but if telnet or ssh work, I can try a bunch of things if anyone needs any info from it.
I am familiar with Linux, but not an expert, in case anyone assigns some expert task to me.
The firmware is already built as a snapshot. Use the "Firmware OpenWrt Snapshot Install" link on the page that @frollic linked.
Since it is snapshot firmware, there will be no web interface at first, you'll need to ssh to access the router and install LuCI.
Note that if you flash this, and it reboots back to stock firmware, you need to flip the alternate boot system from B to A as described in the git commit. To do that, download a stock firmware from the Linksys site and flash it, then flash OpenWrt again.