The only way to strip Chrome of their monopoly power is to remove their decisionmaking mattering: Switch all your stuff on your websites to JXL, let Chrome provide a bad experience, and then it's up to them if they fix it.
Maybe with a banner like "You are using Chrome. You might have a degraded experience due to the lack of support for better image formats. Consider Firefox".
In either case: Have Chrome telemetry report home that "user could have 20% faster page load with JXL support".
Nothing changes for Chrome users, especially sites using the <picture> element where the first supported image format is used.
I’m sure YouTubers and tech sites will love to do Safari vs Chrome (and Co.) content to spread the message that Chrome is inferior.
(WASM) Polyfill and we're done.
Any resemblance with previous events would be totally unintentional, of course :-)