how to insert elements on slider

Hello to all,
ive some experience in wp dev, but im not an expert of the framework, and before spending a lot of time id like to understand if its possible doing a thing simple on my mind but maybe too expensive in terms of cost of time for get the result!

I’ve a theme that include some widget for build up the homepage, like some testimonials, or other specific structure for “team members” or “activities” etc.

These widget didnt came as “post” or specific “post type”, there is a way to convert them as a structure that i can put on standard plugin sliders even by coding…
any help to point me in the right direction will be very wellcome