Nick here from Shopify.
You are correct in saying that the process can take up to 48 hrs in some cases for everything to sync. Can I ask when you initiated the process?
Facebook will notify you by email once they have reviewed your store to let you know one way or another if they have approved you or not.
Something else to remember is that these decisions are made by Facebook directly where Shopify has no control in the outcome.
If you initiated the process more than 48 hrs ago and haven't received any word from Facebook. It could be worth trying the syncing process again. There is only one way to add the Facebook sales channel where there is a Shopify help guide for it, which you can see here.
Hope this helps and it gets synced sooner than later.
All the best, Nick