Raw compute wise, you're almost right (almost because real cloud hosts aren't overprovisioned, you get the full CPU/memory/disk reserved for you).

But you actually need more than compute. You might need a database, cache, message broker, scheduler, to send emails, and a million other things you can always DIY with FOSS software, but take time. If you have more money than time, get off the shelf services that provide those with guarantees and maintenance; if not, the DIY route is also great for learning.