[pepsi-not-coke]

I proposed a similar idea (before WASM was a thing) in 2015 on the W3 TAG mailing list, where I simply said why can't the site owners tell the user's browser what browser engine, including specialized ones, should be loaded to render and interact with their site/app. It was dismissed with idiots from the browser vendors saying it's impossible because of ABI compatibility etc. I kid you not, 10 years ago, and then someone from Meta tweeted the same idea 2 years later (the guy behind Slick Carousel) when WASM was a thing, but he did not specify WASM, and I told him that I had brought it up, too. This is not a new idea, but I'm glad to see renewed interest and WASM as the way to do it.

[immibis]

The Content-Type header tells your Firefox 3 browser whether to use the HTML rendering engine, the XHTML rendering engine, the XUL rendering engine, or the Adobe Flash rendering engine. Is that what you mean?

[pepsi-not-coke]

No, that does not solve the problem of the Google monopoly. Not a fixed set contained within one browser engine, but the browser engine itself, like Webkit vs some other engine vs some specialized engines. If your engine-host browser does not have a give engine or specific version of an engine it downloads it and caches it. WASM/Wayland makes the idea feasible, loading lightweight WASM modules.