1. Can I import a hardware wallet into a mobile wallet like metamask?
What is the point of having a hardware wallet when your want to import its seed phrase into web wallet like metamask? That defeat the purpose of having a hardware wallet which are still better than online wallets.
2. What are the risks involved in doing this?
Private key would be more vulnerable to online attack.
3. I want to bridge Arbitrum will it work on hardware wallet?
This is the question you supposed to ask. You can connect the hardware wallet with wallets like metamask (not importing the seed phrase, but using it as a wallet to operate the hardware wallet).