There's PYREX (original, all caps), and there's pyrex (lower case, licensed to many different manufacturers). https://youtube.com/shorts/f-nfX1BXss0?feature=share3
I learned that a couple years ago when I was looking to possibly use a pie plate as a wood stove window. Hey, high temp ceramic is expensive!
The old elm wood stoves used a Pyrex pie plate for a view on their stove doors. I always thought that was pretty neat.