I just sent a PR https://github.com/armedbear/abcl/pull/635 that allows to optionally define different UIs for the visualize and control stepping process of abcl-stepper.

I also made an initial implementation to be used as a guide for more UI if someone else is interested https://gitlab.com/cl-projects/abcl-visual-stepper. This version uses HTMX and websockets. 

The UI is not quite beautiful and it is still a work in progress allowing syntax highlighting in the browser and other little niceties to the stepper user. Probably someone with more UI/UX experience can make a better UI and can do it by using the generic functions defined in the stepper code and defining his own protocol.

I believe this idea could be also generalized for other components of the system (inspector, debugger, REPL, etc)

Any feedback is appreciated,

Thanks