“What Platform or Ecosystem?” is a very good question to ask. I am also skeptical that bootstrapping Scala Native into its own platform will be feasible.
One (to me) interesting possibility is to target the Python ecosystem. By which I mean Python libraries + the native libaries supported by it. There’s a lot of interesting stuff in that area. Swift is making good use of it, and the way this is done is all publicly accessible as far as I can see.