Does anyone use Square POS for in-store and shopify for online?

Retail & Point of Sale
2

What exactly do you need them to connect? Do you need to sync inventory, customers, anything else? More than likely you will need an omnichannel management software to act as the go-between to get your inventory to sync. There are multiple vendors that offer this service, but that will only add another monthly cost to your operations, which it sounds like you are trying to avoid.