Where can I swap sat for BTC from a Lightning wallet over to BTC?
Discussion
You can use the Boltz exchange: https://boltz.exchange/
But, be mindful of the BTC on-chain fees. With Boltz you'd pay for a high-priority confirmation; The highest fees.
Another option is to swap "Lightning BTC" for Liquid BTC, which you can also do on the Boltz exchange. For this you need Liquid wallet to receive the funds. Then, you "peg-out" of Liquid BTC to "on-chain BTC". This can be a lower-fee option because the Lightning -> Liquid swap is cheap, and the Liquid "peg-out" using sideswap.io allows you to set a priority for the BTC transaction. Therefore, if you can afford to wait, this two-step process can save some sats.