Hi @ThatsEnts thank you for reaching out about this and for also sharing your feedback about the issue with your card reader. I can definitely understand how 8 days without a card reader for your in person shop is not ideal.
I took a look at Zettleās website and it looks like Zettle has their own POS system that would be required if you wanted to use their payment gateway for in person sales. You can see more about this on their website here: Taking card and contactless payments | Zettle. The Shopify POS system can only accept Shopify Payments and if you wish to use a third party payment gateway you will need to invest in a card reader designed for that payment gateway.
I would contact Zettle to learn more about their requirements for this.