Earlier quoted context omitted.
That's already happening today. https://grapheneos.org/ But for the reason an antiquated os like postmarketos are suggested is that the project is being opportunistic thinking this is a chance they can be relevant. Additionally, the population of HN has more sentimental view on these legacy operating systems and view it as a chance to go back to the past and use software they are familiar with.
I really wanted to like Graphene OS but I ended up bouncing off it due to a few major pain points that badly effected battery life. - Using the default 5g setting resulted in far worse battery life than stock, telling people to choose 4g isn't a solution. They desperately need something like the adaptive connectivity service. - Using Homeassistant's GPS tracking feature just destroyed the battery life, even switching…
I ended up using my public ip address in combination with a list of known ips for home and work and such, and building my HA automations around that. I wanted to do it with wifi SSID's, but that also requires the location permission and triggers the indicator (which is understandable, just wish I could still read SSID's with location services disabled entirely) (or, just let me disable the gps antenna and leave everything else).