I had a random encounter with with Lars Thomas Hansen, which works on Webassembly (wasm) at the Mozilla foundation. So I asked what he thought of the idea of using unikernels in browsers. Now I have a better understanding of why it isn’t really feasible.
I guess the binary could be built on demand and supporting 99% of the devices out there would be possible (if one supports i386 and ARM32) with on demand compilation targeting each device and taking the features of that platform into account. However, it would’t be as easy to leverage things like edge caching nodes to handle scalability and network performance. wasm OTOH can leverage CDNs and such in a robust fashion.