How to tell if your wallet is compromised?

I've got a Ledger and use my wallet primarily to mint my own NFT's on various marketplaces. To the best of my knowledge, I don't think I have connected or granted access to any dApps that may be dodgy. However, I'm feeling a little paranoid and I wonder if there's a way or some sort of tool that helps you verify if your wattet has been compromised. Is this a thing? Is there also a way to revoke access to dApps?

Someone also suggested I consider creating a multi-sig wallet for even tighter security. Is there a way to convert my existing wallet to multi-sig or will I have to make a new wallet?