[withoutboats3]

tokio supports a single threaded executor when you really need it, and its not even hard. It's called a LocalSet in tokio's API:

https://docs.rs/tokio/latest/tokio/task/struct.LocalSet.html...

[basro]

This is true but the rest of the ecosystem is not built for it.

If you try to use axum in this way you'd still need to use send and sync all over the place.