Pi doesn't even have its own blockchain yet, and its ecosystem is very poor. It originated from an idea and is only supported by community belief. It seems more like a memecoin than a native token of a vibrant blockchain ecosystem.
PI does have its own blockchain, how else do you think they are migrating people to the mainnet then? Those who had mined coins through the app and completed KYC got their coins migrated to the mainnet in their wallet, and then they could send them from their to exchanges so that they can trade them, and when you are sending your PI coins from the wallet to an exchange, the network used for that is PI network, so they do have their own blockchain.
About the ecosystem and the use cases of their coin, I also agree that they don't currently have any use cases. Their coin is not accepted anywhere; it's only tradable in some exchanges, and that's it. Other than that, it doesn't have any utility so far, so even though it's not a meme coin, but it doesn't have much utility for now.