Even still, whatever high salaries they do give us just flow right back into the neighborhoods through insane property values and other cost-of-living expenses that negate any gains. So, it’s always just the few of us who can win that lottery and truly break out of the cycle.
Every company I've worked for has had very explicit rules that say, you must get written permission from someone at some director or VP level sign off on your "side project," open source or not.
You might want to check your company guidelines around this just to make sure you're safe.
You break out of the cycle by selling your HCOL home and moving to LCOL after a few years. That HCOL home will have appreciated fast enough given the original purchase price that the growth alone would easily pay for a comparable home in a LCOL area. This is the story of my village in Texas, where Cali people have been buying literal mansions after moving out of their shitboxes in LA and the Bay Area.