I'm not super familiar with Heroku and similar platforms, but if I don't rent EC2s (which I take to mean what you meant by "VMs"), how do I host and serve bespo

I'm not super familiar with Heroku and similar platforms, but if I don't rent EC2s (which I take to mean what you meant by "VMs"), how do I host and serve bespoke backend components? Even if all it does is suck data in, perform some computation, and send it off somewhere else - are you saying there are SAAS providers that are better equipped for this?