We will only go through designs about filters. I want you to keep in mind that not all item arrays need filters.
5 things to be mindful of when you design filters
Skeleton screens (as splash screens), when used to indicate that a screen is loading, are perceived as being shorter in duration when compared against a blank screen (our control) and a spinner — but not by much.
Everything you need to know about skeleton screens
Visibility of system status is one of the most important principles in user interface design.
Everything you need to know about Loading Animations
Stop Using A Loading Spinner, There's Something Better
Progress Indicators in Mobile UX Design - Usersnap
How To Make Users Think Your App Loads Faster
10 Creative Loading Indicators
Good UX example about product design