How can I purchase an Apple Sim for my 4th Gen Mini with no Apple store open?

Here are some further details as to making contact with Apple Support:

Contact Apple for support and service - Apple Support

Alternatively, the Apple Support App will help you to initiate a case with the Support Team:

https://apps.apple.com/gb/app/apple-support/id1130498044

I hope this additional information is more helpful in your quest.

Apple SIM cards, should they need to be replaced, can be obtained from an Apple Store. Most Apple Stores have now reopened.

Alternatively, your might directly contact Apple Support - who may be able to supply a replacement Apple SIM card for your iPad. The link to Contact Support is at top-right of this page.

I’m sorry that you believe my initial reply to be unhelpful.

Apple Stores may well be closed in Florida. Your location wasn’t declared in your original post - and majority of Apple Stores are open in other regions and countries.

And no, you did not use the Contact Support link to post to this Community. Nobody here is from, or represents, Apple; contributors here are all end-user customers, just like you. We offer assistance with technical questions where we can, directing you to other sources of information and assistance if needed.

You’re very welcome. I’m delighted to learn that your problem is now (or will very shortly) be fully resolved.