Can I sync products from to multiple Shopify locations to different Square accounts.
No, we can only connect locations to locations and accounts to accounts.

Why my barcode scanner doesn't recognise the products QuickSync created?
if this is happening, please reach out to Square directly on this link.

Can I use Square as a payment gateway?
Unfortunately Shopify doesn’t allow Square payments as of now. Here is the full list of payment gateways supported by shopify - www.shopify.com/payment-gateways/united-states

Can I sync my Square appointments?
No, we don't sync that.

I have products with over 100 variants on Square, but Shopify only allows up to 100. Is there a workaround?
The only workaround is to break down your product with more than 100 variants into small separate products. After this, you should be able to sync it.