it's bootstrapped off of GHC.
it was only using ChezScheme as an optimizing compiler backend.
(i created a PR to refactor their build system to reify the bootstrap process all the way down from GHC. it basically generalized the normal build workflow of Idris2 to be able to animate the entire bootstrap chain from GHC. sadly, it was pretty much ignored, and later abandoned: https://github.com/idris-lang/Idris2/pull/1990)
From the Idris 2 documentation:
>> Can Idris 2 compile itself?
> Yes, Idris 2 is implemented in Idris 2. By default, it targets Chez Scheme,
> so you can bootstrap from the generated Scheme code, as described in Section
> Getting Started.
Racket is only hard if it's not your first language. Kids can also learn it.