reCAPTCHA at Checkout?

I know it is possible to add reCaptcha to newsletter or other forms, but is it possible to add this same block in the checkout?

We offer products which are very limited, and often times real customers who attempted to check out manually are not fast enough compared to those who use bots to quickly fill all of the fields. It would make our releases more fair if users without bots also stood a chance at purchasing our items.

This sent possible. Squarespace lock their checkout down and don't allow anyone to add code, so it isn’t possible to add a reCaptcha.

You won't find a way around this until Squarespace do something about it. To raise a feature request, open a ticket through Customer Support.