> as you even admit, many/most of them will find their phones unusable with vanilla GOS and immediately follow the GOS user guide to install Google Play

I installed the Play Services right away, just like I installed microG right away on a LineageOS system (I don't know about iodeOS, but /e/OS comes with microG by default). In terms of privacy, I don't think it is very different: microG is an open source implementation of the Play Services, that also contacts the Google servers. Many will use something like the Aurora store, which is a client for the Play Store. Etc.

GrapheneOS has proxies, e.g. for the location service. They are doing a lot for privacy, that's very clear.

> I think iodéOS and /e/OS are more in line with what I want from a mobile OS.

And that's your right. I think that GrapheneOS is more secure, and not less private than those. Actually in my experience with /e/OS, it was less secure than Stock Android (though more private, admittedly).