This is the site where I mine grams but I'm still not 100% sure it's legit, I found it on etoro yesterday but they didn't start to work with it yet or it was paused idk. If there's someone who knows more please comment!
I'm not an expert in cryptocurrency, but as far as I know, GRAM was Telegram's attempt to have something similar to Facebook's Libra. The project was shut down last year. You can read more details in the following articles: