For Shopify fashion stores, what would make virtual try on a clear yes?

I am working on TryOnPod, a virtual fitting room app for Shopify. The idea is that shoppers can upload one photo, then try on different items and outfits in a floating pod while they browse.

I am trying to understand how store owners and marketers think about virtual try on right now.

If you run or work with a fashion, accessories, or other wearable Shopify store:

• What is your biggest headache with size, fit or returns today?

• Have you tried any virtual try on tools in the past? What did you like or dislike?

• What is the one thing a tool like this would have to do for you to say "yes, I will install it on my store"?

Honest feedback is very welcome, including reasons you would not use virtual try on at all.