> I do wonder what a language with the same “taste” and minimalism as Scheme but embracing the actor model would look like.

There is Spritely Goblins: https://spritely.institute/goblins/

In terms of modern concurrent actors, in addition to Spritely Goblins there is also Termite, a restricted Scheme with Erlang-like concurrency semantics that now comes with the Gambit distribution.