For my own ROM [1] I spent days and a hundred of euros optimizing the cost of building by trying various cloud providers (fwiw my current best spot is scaleway GP instance with 600GB local SSD). As of today, I'm still at 6€ per builds (For standard ROM devs, that should be cut down to 2€ I'd say). There is simply no way I can afford a CI. (well if someone wants to give me money for that, please do!) I do my best to isolate components and have at least some kind of CI where I can, but that's hard work (And doing CI is my day job, and I consider myself rather good in it)
Even android's own CI is very far from what you'd call a modern CI. They basically just build master once every hour and pray for the best, and let the build cop fix that. They do have a mechanism where they try to build CLs in batches, but "try" is the keyword.
[1] https://github.com/phhusson/treble_experimentations/wiki
I have always had the same issue with hackintosh and DD-WRT.
I run DD-WRT on a router, a kong build, but always have the lingering doubt about security.
Why is it some communities still work like this? With Android dev, sometimes there's even some source on GitHub, but still a forum post is the main place to find the latest version, with the actual download from some questionable-looking download site. If you're lucky they include sha hashes at least.
I've installed a handful of custom ROMs on 3 or 4 devices - most recently resurrecting my old TF101 to run modern Firefox - but I don't think I've ever seen anything like an automated build for one of these. Really, many don't even post source code.
Is there anyone doing this type of Android dev in a "modern" best practices way like most other open source (public git, CI, maybe issue tracker and pull requests)? Why doesn't this catch on more?