My QoL suggestion - Inventory button

I don't believe a feature like this is necessary. Either you have the desired parts, or you don't. In the case of the latter, you either sim battles for the parts you need or purchase them through other means. That's why there's a whole section of "here's where to find these parts" that shows up and can purchase instead of needing to go out and hunt through the entirety of the store for one specific bit.