Most will take the trade in phones, refurbish them, and resale them on a used market platform like backmarket. Anything not worth reselling I think is recycled.

Source: https://youtu.be/WHqxBlFuIXA?si=KC4xxIeI4qPf60QS

One of my friends just signed up 29 days ago and got in so they are definitely catching up. I was on the waitlist for a year and a half

This is why I like services like beeper bringing iMessage support over to android. I get to use the phone like, but also make my friends happy by not messing up the blue bubbles