Pages Showcase Block

I’m trying to create a block similar the Item Showcase that would allow you to select a few pages to showcase on the site. Instead of selecting attachments it would let you select pages and the media item to display in the showcase.

My first question is, does something like this exists already?
If not, do you have some advice on whether or not this is doable and maybe some direction on where to start?

Thanks!

Edit:
I should add that I have customized the ItemShowcase module already and am somewhat familiar with the module development. However, I’m getting stuck on how to modify $view->blockAttachmentsForm($block) in application/src/Site/BlockLayout/ItemShowcase.php and the corresponding common/attachments-form.phtml in my own module to display and select pages rather than attachments.

The “attachment” system itself is only ever going to work with Items and Media, that type of thing. You can make a block that deals with Pages, but the page(s) you select would just be stored as extra data on your block, not as “attachments” per se.

So, it probably doesn’t really make sense to think of things in terms of altering the existing attachment stuff, rather starting from scratch on what you want to do.