They have containers, does that count?
If you’re specifically thinking of native ephemeral workers with very fast startup, it seems like those would have to be sandboxed somehow, and WebAssembly seems like a decent solution. Is there really a significant native code gap between WebAssembly workers and native containers?
Containers seem to only be "Available on Workers Paid plan", whereas Vercel supports it on the hobby account as well.
Kind of relevant on those cheapskate projects that only start paying licenses after the SOW is signed, but already expect some kind of prototyping in place.
WebAssembly is a solution looking for a problem outside the browser, with worse development experience.
If I want bytecode based runtimes, I already have them with first class development experience, and decades of deployment experience, between Erlang, JVM and CLR.
Haven't used Vercel but back in the Heroku/CloudFoundry days it was pretty easy to jam arbitrary binaries into the runtime containers and some of the build packs were flexible enough you could override most of the functionality.
Not sure if that's possible/how easy it is on Vercel