I hope it becomes a bit more mainstream now. Some custom roms like lineage are very hostile to it because they're afraid Google will do more against them if they include it. You can't even mention it in their community or you will get kicked. It's nothing nasty though, it's just a bare minimum implementation of google play services remade in open source, withholding as much information as possible and giving you the ability to fake things like device model and attestation "safetynet". Luckily there's a fork from the microg team https://lineage.microg.org/ . So this is what I normally use.
But it's a great middle-ground, you can still use google push and you replace all the other parts like the location DB with privacy-conscious alternatives (though with the abolition of mozilla's wifi location database this has become harder).
I'm not a fan of /e/ though, especially because of the name that makes it impossible to google anything. And they are often years behind in android versions.