Thank you.
Its not possible to stake any other coins/tokens in a POS model because most of the time they prefer the native token/coin to be locked up.
Does this mean, that there are the designers of the blockchain, that decide if only the native coin is available for staking and no tokens. So can you say any blockchain, that allows also to stake any token?
To simplify your answer. Let's go back in time, when Ethereum was still POW. Ethereum was the blockchain network and ETH was the native coin of the network. In the same network there were thousands of ERC20 tokens built on it but all those coins and network depended on the native coin Ether for deployment of smart contracts, transaction fees etc.
The only coin that could be mined was ETH and the mining rewards we also in ETH not USDT, USDC, BAT or any other token. The same applies to the current POS Algorithm. On the Ethereum network, you only stake ETH.