Where can I find a few sovereigns like shot glass, magnets, and or key chains

They have a souvenir shop in the mall on the 2nd and 3rd floor

Start walking and exploring. Part of the fun and experience of MOA

It would be hard to NOT find those kind of items in almost every other store! But there are a few official MOA stores around

I saw some on the 3rd floor

Tourist stores all over the mall. You'll have plenty options

There are gift shops on practically every level of the mall with that stuff. Every big restaurant has their own gift shop as well.

There are stores scattered everywhere throughout the mall with tourist junk.