Randomly found out about this extension in a TikTok and have been playing around with it for a couple of hours. If you have a competitor that has a Shopify store, download the extension Koala Inspector and it will show you the apps they have downloaded, the best sellers, price range, etc. I don't think it's 100% accurate (for example, I did it against my store and 3/5 "best sellers" were actually best sellers, not sure why they pulled the other two) and it just pulls the apps the Shopify store has downloaded, not necessarily in use. It is fun to check out competitors though!
Edit: Just discovered CommerceInspector and it seems a lot more accurate.