I stll have a lot of ideas for this and want to continue there. Unfortunately I have had very little to no time for this project lately. :-/
I first believed fdroid client could move to SharedUser Id (with privileged ext) which always break upgrading process; thx to @hans explanation it won’t:
F-Droid and Privileged Extension should be as isolated from each other
as possible to better enforce the security limitations. They should
always be signed by separate keys, with Privileged Extension signed by
the ROM and F-Droid signed by an app key. If you are shipping the
official F-Droid builds, then it must ship with the F-Droid signature.
, so 102.3 old signed version is still fine, for now, as a prebuilt in rom; will add privileged ext in my next microG Treble rom
v0.102.3 still works but has known bugs and security issues that have
been fixed in more recent versions.