Also for that I was thinking about building an app to enable easy FIAT cash to Lightning transaction, I am studying CivKit. It seems it can help achieving this.

I am imagining a software where there are peers who provide liquidity on lightning network, on mainnet and on CEX as well, an application which runs on Umbrella for example.. which facilitates orders on order books in order to purchase back those sats sent on lightning sold for fiat cash