Does a “warning, cert issued by a government agency” count as additional validation?

From what I gather they can’t do that either.

Or maybe everyone is going to use cert pinning now.

Same as above. This would be effectively “adicional validations on the certificates”.

Or Firefox is going to stop trusting all CAs and make you verify each CA yourself. Which is a terrible idea for the average user.

Would be legal but annoying. Bet they would legislate to force their CAs / be exempt from that user verification.