The fact that they want to create a special coin for this purpose should be red flag enough. You don't need a new coin for this, you just need an app that provides infrastructure. If you want to get paid, either make it donationware, or let a small percentage, that the user chooses, of the fees go to you.
I used to be a big believer in if a coin had a real world company/app whatever behind it then it was far more legit and had potential far more that any pure currency coin. This was my biggest lesson in crypto I had to learn and found most were the biggest scams around and were using the real world use to pump and push their shitcoin, getgems was one of the worst.
