In almost all cloud deployment, whether transparently or not, you'll have a hypervisor/VM underneath for hardware-level/strong isolation reasons. Using wasm on top of that stack only for isolation purposes might not be the best use of it. Having said that, if wasm is useful for other reasons (e.g., you need to run wasm blobs on behalf of your users/customers), then my (admittedly biased) view is that you should run these in an extremely specialized VM, that has the ability to run the blob and little else.
If you do this, it is entirely possible to have a VM that can run wasm and still only consume a few MBs and cold start/scale to 0 in milliseconds. On kraft.cloud we do this (eg, https://docs.kraft.cloud/guides/wazero/ , wazero, 20ms cold start).
In almost all cloud deployment, whether transparently or not, you'll have a hypervisor/VM underneath for hardware-level/strong isolation reasons. Using wasm on top of that stack only for isolation purposes might not be the best use of it. Having said that, if wasm is useful for other reasons (e.g., you need to run wasm blobs on behalf of your users/customers), then my (admittedly biased) view is that you should run these in an extremely specialized VM, that has the ability to run the blob and little else.
If you do this, it is entirely possible to have a VM that can run wasm and still only consume a few MBs and cold start/scale to 0 in milliseconds. On kraft.cloud we do this (eg, https://docs.kraft.cloud/guides/wazero/ , wazero, 20ms cold start).