Ensuring data security before recycling a broken iPhone

Apple no longer has the same connection ports for these iPhones, so I have no way to connect it to my MacBook to try to do a factory reset or extract the files

Even if you had the correct lightning cable to connect to your MacBook, you would not be able to "see" anything or "access" any data on the phone with a broken screen.

How can I make sure that any information that might still be accessible is no longer accessible when I send it to be recycled?

Even if someone went to the trouble of taking the phone apart and started messing with the parts, they would not be able to access any of the data on the phone.

If you are the paranoid type, put the phone in a vise and crush it before you drop it in the recycle bin or drop it off at the Apple Store.

Even if you could connect your highly broken phone to you computer, you couldn't erase it or do anything with it since it's smashed. If you recycle it with Apple, your data will be safe.