I see. So you want a lightning channel to be established between a user and a canister on the IC. Or, alternatively, between one of the big lightning nodes that offer routing and a canister and then the user can indirectly route Btc to the canister.
First of all I would love to see this implemented just because it is cool. But we also have to think if it really gives you the benefits that you think it does. The user already has to have the Btc locked in the lightning channel in advance before the need for a real-time trade occurs. Then the user might just as well lock the Btc in the canister-DEX directly. With centralized exchanges you want to take funds off the exchange as quick as possible to reduce risk but with a DEX in a canister the situation is different. So the need for a lightning channel may be reduced.
With lightning in general the problem is always the other direction, taking funds out, because the exchange cannot keep channels with all its users that are all funded on the exchange side.
Technically I think there are still some open question if this can really be done in both direction. There is some problem with the way that HTLCs work. The IC can do threshold signing but cannot create hashed secrets in a distributed way that are later to be revealed. This has to be investigated in detail. Maybe there are future lightning version that use a different hash function who’s computation can be distributed. Or there might be some hybrid solution that runs almost but not entirely on the IC. That’s TBD.