Thanks. But it seems liquid is something that has not really caught up, so that I could spend it at merchants. 
Even some f my Bitcoin friends who can take sats or lightning, cannot seem to accept liquid. 

spiderman

i do not see direct method to swap in and out. but Zeus offers the option.

But the goal behind the question is to find whether there is an in app or a cheaper option.

I use liquid in the middle for making it cheaper, though it is centralized by 15 federations.

bitcoin

How to Swap Out from Lightning to On Chain Coins in Blockstream?

i do not see direct method to swap in and out. but Zeus offers the option.
By the way, 

>But the goal behind the question is to find whether there is an in app or a cheaper option.

I use liquid in the middle for making it cheaper, though it is centralized by 15 federations.  