Custom Functions with Dynamic Data

I am looking for a way to add my own custom data to query loops & post templates via my custom functions that I wrote.

However I don't see the option to be able to add this anywhere.

I know that I can use a shortcode to pass my function into the section, however it seems like a hacky workaround as I would rather just be able to type my function name and the arguments that I want to pass in.

Is this something that is possible? Or can it be something added to the feature roadmap?