The hurdle to providing on/offchain swap P2P is that there's (currently) no easy way to escrow the LN without doing it custodial.
If you see the "Crypto-to-crypto methods" of this list includes three P2P exchanges, but the two non-custodial, Bisq and HodlHodl, provide LN only as pmt method, and the remaining one is custodial ... they let you deposit and withdraw with LN, and you pay a fee (1%) when withdrawing BTC via LN.
In reviewing that, ... it looks like Bisq does not support LN even as a payment method. There is a fork of Bisq, "Misq", ... or even Bisq 2.0, in-development that will handle multiple protocols, including LN.
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