Yes, of course in theory nested state machines should be able to model this. I feel like adding more complexity and bending the rules is a bit of a concession.

Back in the days we implemented HSM helper classes in about 500 LoC and generated them from Enterprise Architect. No need to write a GUI yourself, but better to have a visual for documentation and review. Worked very well until we replaced EA with docs-as-code, now I miss that there is no nice simulator and Modeler for that workflow.