Will Shibarium rely on PoS or PoW?

Out of curiosity, when Shibarium is released as either it’s L2 or blockchain, whatever they decide to do, will it rely on PoW or PoS for trade validation? (IE Miners Fee).

I know you cannot mine SHIB, it’s already minted, but I know you have to validate transactions in the ledger (?) And thats comes with a gas fee, which is then paid to validators on PoS.

And if shibarium is PoS how much would have to be staked to be a validator?