Nick here from Shopify.
Can I ask what country you are based in? The reason I ask is that the types and models of POS hardware are different depending on where you are located. If you are in the USA for example then you can use the Shopify hardware seen here.
If you are outside of the USA, then it might be worth looking through the hardware from specific countries which is linked in the Shopify POS hardware overview here.
Looking forward to hearing from you.
All the best, Nick