You might want to look at something like the Fantastically Good Event Parser action for both platforms. Lets you just type the event details in natural language and it converts it to the appropriate event fields.
The Event step does not work on Mac, that is true. Apple does not provide a similar API on Mac at this time.
It is possible to create a similar (though more limited) thing with prompts and scripting in Drafts, but I haven’t seen any examples…and the natural language approach tends to be a lot less clunky in practice once you get accustomed to it.