A straightforward solution seems to migrate to fly.io to do the same (although I am not exactly sure about its free tier).
My question is, if there are any better services, more reliable, faster, without invoking node.js every time? A static website provider that allows to configure the http headers, or they allow WASM default. (e.g. github pages can't run WASM)
But does https://docs.netlify.com/routing/headers/ do what you need?