hello !
Yes, it is not easy to find informations / samples !
on my side, I used to the extension from taifun but I change to the in app billing from kodular recently ! (Cause, It seems the taifun extension was not still supported)
So, You can find here my blocks on the in app billing component !
Do not hesitate to tell me if it is ok for you or if I have make mistakes !!!
Enjoy 