I've been using Google's Cloud Run for production a while now and can recommend as a friendlier alternative. It also includes a free-tier which might be ideal for side projects.
I think C++20 coroutines are awesome! They need a bit of getting used to but helps to write very readable code, specially when having to mix C++ with C callbacks.
I'm an entrepreneur (luckily with one successful tech startup) and along the way I've had many failures. I've also helped many other startups on their journeys to becoming very successful and the truth is your journey is something you will need to decide.
But, from my experience I've now realised you shouldn't work on your idea with your own money. It's great if you have enough savings to do try something you love but the point of a startup is to make money (unless it's a non-profit). In order to make money you will need to convince someone else that it's a good idea and pay for it.
So, validate your idea before you go full-time and get some early customers. There are many ways to do a "safe" startup. There's always a risk but you can make sure you don't end up worse after a failed venture.
I'm new to HN but I suspect there are many who'd be willing to help you and complement your skills to make your idea successful (I'm one of them).