Yes and no.
Yes: The `ffi/unsafe/vm` library provides access to Chez Scheme's
`eval`, so you can use `(vm-eval '(fork-thread ...))`. Even more
directly, you can use the `ffi/unsafe/os-thread` library to create a
Chez Scheme thread.
No: Accessing Chez Scheme directly is unsafe, because you can break
Racket invariants, and there are some limitations on using Chez Scheme
functions in Racket and vice versa. See `vm-primitive` for more
information.
Matthew