Preference to establish HTTP/3 connection without need to upgrade from HTTP/2 for certain sites

[serfreeman1337]

Right now firefox first establishes HTTP/2 connection, looks for Alt-Svc header for advertised HTTP/3 support and then attempts HTTP/3 connection. It would be nice, If there will be preference to specify domains with known HTTP/3 support, so firefox will try HTTP/3 connection with them first without need to establish HTTP/2.

Looks like network.http.http3.alt-svc-mapping-for-testing pref does exactly that, but it lacks wildcard support. I would like to have it working with wilcards to: *.google.com;h3=:443,*.googleapis.com;h3=:443,*.facebook.com;h3=:443,*.fbcdn.net;h3=:443 etc.

Forcing HTTP/3 connection first allows to bypass some restrictions from ISP.

[unitythemaker]

+1 for this. Extremely important for me to bypass stupid government restrictions. They utilize DPI to both track all websites I am visiting and at the same time block websites by capturing Client Hello. Firefox lacking wildcard support is very frustrating as I need to utilize VPN when there are too many subdomains to add.