It's possible combating it in terms of pushing for different standards could be sufficient. More little guys at the table means more sway to push things like JPEG XL through.

Only if they’re bringing real users in sufficient numbers to affect site owners’ decisions. Right now, “the web” is what Chrome and Safari want it to be. Mozilla largely ceded their seat at that table but is probably the closest to being relevant again if they can come up with a better pitch to users.