Pyrex that can be used in an instant pot
That is commonly done, and yes, any pyrex is fine for it although metal has an advantage in that it wouldn't require extra time. Anytime you use glass, pyrex, ceramic or any other heat absorbent material for "pot in pot" cooking, add ~5 minutes to the time under pressure. Anything that is safe to use in the oven is safe to use in the Instant Pot.  Whatever you use inside the liner of the Instant Pot as your cooking vessel, use the trivet and add water (at least 1 1/2 cups or so) to the inner pot of the Instant Pot, and be sure there is some room (it doesn't need to be much) to allow steam to pass between your inner pot and the Instant Pot liner.

Here's more on the subject of 'pot in pot' cooking.