And please do you know what will be the staking reward? I know that Cardano will give 3-4% profit per year. But what about Ethereum or Matic.
With the recent Matic dump I am thinking about buying it for future´s profit.

The same thing that is in my mind. I am also interested on Ethereum, Matic and Cardano but I don't think I am investing more money apart from my present portfolio if the yearly profit is too low. I am expecting Ethereum return will be low too. Matic is a new coin and made its own bear and bull wars just this year. Matic might be giving us a good profit here.