ILikePigeons
GSI (Generic System Image) ROM-s do have bare-bones apps due to their nature of being mostly designed for developers. That won’t really be a problem as you can just install better alternatives to those apps. The problem with these ROM-s is that they most likely won’t have drivers for the camera for example. Also the phone has to be Treble-compliant and it has to come with Android 9 (ie. it has to be preinstalled, devices that have been upgraded to Android 9 aren’t supported.)
It is definitely very performant. However, it was a pain to set up when I first tried to use it. First installing it, then installing an ARM to x86 compatibility layer, and then certifying the device for Google Play to work (which in hindsight isn’t necessary considering that Aurora Store exists.)