Do you mean that you want to buy Bitcoin within a Lightning wallet?

You can use a KYC’d custodial provider like Strike or CashApp (if you’re US-based) to purchase and send Bitcoin on the Lightning network. These are very easy-to-use services, with low fees. But of course you give up a few degrees of privacy.

You can also use a peer-to-peer (no KYC) service like nostr:npub1p2psats79rypr8lpnl9t5qdekfp700x660qsgw284xvq4s09lqrqqk3m82 to buy and sell Bitcoin over Lightning. Highly recommend ⚡️🤙