When you have a specific set of colors/items that you want to see in action, you can transition to viewing a replay with that skin, specifically installed in torishop.

This is kind of in-game, but I get what you mean. Maybe a sort of high res gif that plays with the items you want to see?
Supported. But it is kind of already in-game.

you already get to see what it looks like in torishop, but i understand what you mean. pretty sure you can do this by editing your custom files tho.

There is a little bug that allows you to see this,you can go to torishop and select the colours,go into setup>utils>scripts>unloadscripts.lua(or some other script)load,theres a replay,press e

Well why would they want to see in ToriShop if it is already an in-game to see that stuff already?

It is already in the ingame tori shop,he wants to be able to see it better in the ingame torishop

When Torishop cuts you into bits and has a stopped picture, you can't really get the feel for it. It'd be cool to watch some replays with the custom stuff you put on to have better knowledge on whether you like it or not.