Seeking advice on Selling FBM through Shopify

Hey everyone! The company I work for is looking into selling some of our old stock on Amazon to get rid of it. I have looked into the different options and have found that for our needs selling FBM would suite us best. We have a warehouse and shipping set up and I am the one that ships our orders out. I am still trying to narrow down if we will do individual or professional, most likely individual because we have a very specific niche and I just don’t see us selling enough a month to make professional worth it, but we can change that later if need be. My main question right now is which Shopify app does everyone prefer? We are looking for a free app, but everything I have looked into mentions how it’s great for FBA, but I’m not finding anything that specifically mentions FBM.