Your question is a great one that I am happy to help you with. There are a couple of options we can take a look at.
We have a wealth of apps here in our app store which can help with integrating Instagram with your store. I had a look at a few of these apps for you, however they did not mention the feature of the app that you can select only those specific posts. With that being said, I was able to find you one app that many be able to do this. The app I am referring to is Instafeed - Instagram feed, in their benefits section they mention that you can display your content exactly as you wish. In this case, I would suggest reaching out to the developers to get a more concrete answer on if you can only display specific posts rather than the whole feed.
Another option for you is to check with the developers of your theme to see if they can create this custom feature for you. You can reach their support via this link here.
Finally, you can also try hiring an expert to help you further in creating your own integration with the exact feature that you are looking for. Shopify Experts can carry out custom jobs for your store like this, so it is worth a mention.
By the way, did you know we have an amazing resource called Shopify Learn? It’s full of programs, courses and workshops that have been curated by experts and best of all it’s completely free. I’d recommend adding it to your bookmarks. I think you might find the course: Holiday tips and tricks from Instagram and Shopify, featuring Eva Chen to be especially beneficial in the lead up to BCFM this year!
Let me know if you have any questions, happy to help.
Maz | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog