Graal is a confusing landscape, possibly on purpose.
Graal, the technology where they "ahead-of-time" compile your Java program down to a 'native' executable, is a complete non-starter for Ignition. You'd end up with worse performance, worse compile times, a more complicated distribution story, and still be dependent on Oracle's good graces. And possibly break our entire concept of modules.
Liberica NIK appears to be a third party essentially wrapping the open source GraalVM core, with the business model being "do the same thing as Oracle is with Graal, but don't be Oracle". Except, you'd then be entering into a commercial relationship with someone who is not themselves the steward of Graal - giving you two points of failure, not one.
There's also Graal/"Truffle", the polygloat language implementation framework. This is also in a weird spot, because it in some ways it's exactly what we'd want, but (ignoring the licensing sword-of-Damocles) it's also not the instant performance gain Oracle likes to tout in marketing materials. The significant advantages you get with Graal as a Python runtime only work when you're actually running on Graal as a Java virtual machine - which as mentioned above is a nonstarter. It's not actually required to run GraalPy on GraalVM, but it's a significant performance hit if you don't.