It would be great to see a full integration between Square and ResDiary. A lot of restaurants and hospitality venues use ResDiary to take and manage online bookings, and there is a lot of data that would be extremely useful to capture. Other POS systems that link to ResDiary link customer bills to their reservation details, so the system gives an in depth look at customer spend per visit, regularly ordered products, time spent in the venue.
I'm not sure exactly how this would work with Square, and if it is even possible, but I think it is definitely worth considering. I have also raised this as a feature request with ResDiary's support team.
Square Community