to be honest I don't know what to think about it yet, if the creators just want to earn on hype, or maybe NFT is supposed to have some function in the future.

The only function for the NFT's is that a small handful of them have redeemable limited figures attached to the NFT, which you get a token for redeeming later on. The TMNT and Big Boy NFT's have already had a snapshot taken with coins being sent out, so now all of those NFT's have lost their function beyond just being collectible digital art. They also seem to drop drastically in price once the tokens are sent out. That Leonardo grail NFT was going for $400-450 for months before the tokens were given out, for example.