A single sig is plenty secure. Satoshi has a single sig and no one has hacked him.

Multi sig is intended to protect you if you lose one of the keys. For some people and certain situations that is good and they should use it. But multi sig increases the complexity. Most people are better off with one seed with multiple physical copies in different locations.

If you are air gapped your possibility of being hacked remotely is basically zero. The threat then becomes physical. Single sig + passphrase makes a two part secret. Don't keep them together for the evil maid.

Don't become a target by connecting your name and location to a stack. Have multiple wallets and UTXO's, obscure how much you have.