Hey there, baks! Did you end up finding a good tutorial for making eCommerce apps?
You can add snipcart using html iframe
Make buttons with htmliframe with the code of Snipcart Product:
Then export it in html with construct 2, edit the index.html and add to the body the javascript code with your unique API Key:
Finally upload it (For example I use a test wordpress site) and it will works.