I often want some kind of application shell, and those tend to evolve into shitty scripting languages. This is a way of attacking the problem from the other end. And I find the combination of a more static host language and well integrated dynamic scripting language to be a powerful tool.
Was there something about Joker [0] that you didn't find suitable?
Do you have a particular use case in mind for this, OP? It's certainly always a fun and educational exercise to make a Lisp in another language, but the embedded aspect had me wondering if there is a particular problem that you aim to solve by that integration.
I'm picturing something like libguile does with Scheme?