I could not find installation instructions of F-droid as a system app in the website, the top result in a search is this forum thread with a clear and concise first answer:
Are there any reservations about making the installation instructions of F-droid as system App more prominent?
It would be great to promote the OTA ZIP more, I think that would probably best done wherever there are instructions for flashing gapps, like on the ROM’s install instructions page. There are a millions instructions online for how to flash an OTA update, so we don’t want to duplicate that or have to maintain our own.
The goal really is to get ROM projects to build Privileged Extension in as part of the ROM, like Fairphone Open, CopperheadOS, LineageOS for MicroG, Replicant, etc. Then you don’t even have to know that Privileged Extension exists to use it.