@itsclarence’s /e/ OS ROM is an excellent starting point for a /e/ experience. To make the Italian Covid-19 app work, exchange microG Services Core 0.2.10.1940 for microG Services Core version 0.2.12.203315 - as explained several times here in the forum.
I have made very good experiences @itsclarence’ ROMs. Also with @harvey186’s Q-GSI ROM incl.(!) microG Services Core version 0.2.12.203315.
Until an official solution comes from /e/, both ROMs are a good alternative and the user does not have to avoid other CustomROMs or stock Android.