Shortcode for a specific month of the year?

Yes, it’s possible, but it’s not simple. You need to use the date filters and the ID attribute to insert custom date parameters for a specific shortcode instance.

https://www.joedolson.com/articles/docs/mc_filter_date_parameter/

Thanks Joe ?? I’ll look into that. Appreciate you taking the time.
Just out of curiosity, are you available for a paid solution/addon to your plugin if my clients ask?

Yes, certainly.

I’ve sent you messages through Facebook and your website but no response.

I’ve been traveling; apologies for the slow response.