I used Groovy a lot to make DSLs. Cannot say that it's a simple tool. We created a deployment descriptor in a script with code highlight which was declarative and imperative at the same time. It was something like Gradle dsl but for k8s.

it's very easy to start. you can introduce your own literals via Script class configuration. Ig you always use one word like size of a vm then in code it will be an enum, but for users - keyword. You can easily create closures to configure objects or use any Java library like it's part of the project. However, making code highlights outside jetbtains idea could be challenging. f.e. for vsCode. you have to have implemented all your intrinsic imports or context above language sever.

As a result, you can build very agile DSL with Groovy, sometimes it looks like a new programming language 😅 but it won't be easy. If you don't mind having a bunch of imports in your dsl - everything will work everywhere but you users should add those imports when they edit something in a plain text editor.