Lydia API - Firebase

Hello everybody,

I am currently developing an application with in-app payment and I would like to use the API Lydia which offers interesting rates. However, unlike Stripe, I find little information about this.
Could people on this forum tell me about its integration and use with Firebase? This is the first time I posted on this forum, please excuse me in advance if I forget important information.

@ionic/cli-utils  : 1.15.2
ionic (Ionic CLI) : 3.15.2

global packages:

cordova (Cordova CLI) : not installed

local packages:

@ionic/app-scripts : 2.1.3
Cordova Platforms  : android 6.2.3
Ionic Framework    : ionic-angular 3.6.0


Node : v6.11.2
npm  : 3.10.10
OS   : Windows 10