It wasn’t actually. From the docs for Zircon (Fuchsia’s kernel) [0]:

> Zircon targets modern phones and modern personal computers with fast processors, non-trivial amounts of ram with arbitrary peripherals doing open ended computation.

Fuchsia also had a Linux compatibility layer similar to WSL1 at some point. Might still be there?

[0]: https://fuchsia.dev/fuchsia-src/concepts/kernel/zx_and_lk