I heard that hardware wallet can be imported into metamask to use some other network that aren't available on the hardware wallet, is this true?
Hardware wallet can be
connected with other wallets including metamask, but you should never import seed words from your hardware wallet to any other wallet.
It is more secure to use metamask with hardware wallet because it's much harder for your wallet to get hacked, but only if you keep seed words offline and secure.
Other networks could probably work but you need to enter correct parameters for each separate shitcoin blockchain.