They were talking about Nova, not Lawnchair. Nova hasn’t officially been abandoned, but they were purchased by a big data broker a few years ago, and just a few months ago Branch (Nova’s owner) laid off almost all of the Nova Launcher development team.
Nova is not dead, but the writing is on the wall.
https://www.reddit.com/r/VanLife/comments/1avrsbd/rooftop_solar_tracker/
Looks like someone out there had the same idea.
https://www.roboteos.com/shop
They’re currently selling a packaged system for ~$5k, which is a bit pricey, but maybe worth if you’re full time on the van life. Looks like you could probably fit 2 of these units on a typical roof, obstructions permitting. Alternatively you could do one tracker and one flat unit.
It looks like ground based 2-axis tracking systems can be found for ~$500-1k, you’d just need to bring your own expertise to mount it to the roof and program the controls yourself.
Semi-unrelated: others mentioned painting your van white (which you already have) but I’ll raise you one better - consider painting it with an IR-Emissive cooling paint, e.g., https://i2cool.com/
There’s unfortunately few products on the market at this time, but keep your eyes peeled.