Ideally, it shouldn't be too hard to build a side project in such a way that these sorts of infrastructure things are not only a decision that you can defer indefinitely, but also one that you can change later, if you figure out a better way to do it on down the line.

I don't really want to get into a debate over the relative merits of k8s or any other way of doing things in production, but I do want to throw out a general observation: The technologies we use always solve problems that we have. This cuts two ways: If you have a problem, you'll find a technology to solve it. On the other hand, if you have a technology, then soon enough you'll find a problem that it can solve -- even if you have to create the problem for yourself first.