I'm not advocating it (nor am I against it for that matter) but generic shopping cart modules have for a long time supported adding to the cart via URLs. It's q

I'm not advocating it (nor am I against it for that matter) but generic shopping cart modules have for a long time supported adding to the cart via URLs. It's quite a practical design as you just store a shopping cart URL with your product catalog data/page, and was kind of the starting point for "web services" and the composable web (until SOAP and REST ruined it with dogma wrt what you should and shouldn't do).