I think, it is not currently listed on major exchanges like binance because each exchange has standards, which usually include factors such as security measures, user demand, and market liquidity. I think so like that.
As for how long it took other altcoins to launch, it varies a lot. Some were ready soon after announcement, while others took years of development. For me got information about how long Pi lauch it, I don't know because exact reason for Pi long wait time isn't clear. It could be due to the team wanting to rigorously test their product before launch. Given Pi Network uses a unique consensus model which allows energy-efficient mining, they may want to make sure everything's working perfectly before going live.
I think they are not even listed even on a low-quality exchange, so how much more in a major exchange like Binance? A lot of people are supporting the coin but IDK what is running in the mind of its team or devs. They can always choose to get listed on a low-quality exchange first only to compensate their supporters, but it sucks that they didn't do it. I don't even think the requirements for it is strict and the listing fees are high.
It's not about how long the project are launched but it's about their willingness because as you said there are new projects who get listed immediately. I don't know if what Pi is developing or waiting when they are already here for a very long time but I guess it's safe to say that people shouldn't hope for it anymore, or else they will only hurt their selves.