No, it is not safe to use Pyrex glassware as a pressure cooker. Pyrex glass is not designed or intended to withstand the high pressures that occur inside a pressure cooker. Using Pyrex glassware in this manner can result in the glass shattering or exploding, which can lead to serious injuries or damage.
Pressure cookers are specifically engineered to withstand the high pressures generated during cooking, and they are typically constructed from materials such as stainless steel or aluminum that can safely contain the pressure. It is important to use a pressure cooker that is specifically designed and manufactured for this purpose to ensure your safety in the kitchen.
If you are looking for a pressure cooker, I recommend purchasing a dedicated pressure cooker that is approved for pressure cooking and meets the necessary safety standards. Always follow the manufacturer's instructions and guidelines when using any kitchen appliance, including pressure cookers, to ensure safe and proper usage.