I have a Airgradient One (indoor) and a Airgradient Open air (outdoor) and love them. They are Esp boards with esphome configs available. They use readily available component that makes sensors easy to replace when they wear out or loose accuracy over time.
The whole project is open and you can buy the DIY kit and build it yourself or buy a prebuilt one.
The latest release is dated 2 days ago https://github.com/markqvist/Reticulum . Actively supporting is not the same as actively developing.
This should probably be taken as “I am tired of supporting everyone who did not RTFM, too bad if you can’t make it work” and is a totally reasonable thing to do, especially as the project gain more traction.
There is a pretty good community around reticulum that is usually supportive.
I like to have them on esphome. In my case I have them as Bluetooth proxies and also use them with Bermuda BLE triangulation (in addition to the air quality stuff).