Just add your black eyed peas to the Instant Pot with a tablespoon or two of water. Then, cover, and set it to the steam function. Cook for about 5 minutes - adding a minute or two of cook time if you're starting from frozen.
As far as reheating, our favorite way to reheat these black eyed peas is by far the Instant Pot! It warms everything up evenly and is just as easy as popping it in the microwave. Just add your black eyed peas to the Instant Pot with a tablespoon or two of water. Then, cover, and set it to the steam function.
Here's the answer to your questions. Instant Pot frozen black eyed peas should cook up with a 15 minute high pressure cooking time and 15 minutes natural pressure release. Canned beans don't require as much cooking time because they've really already been cooked.