That's the problem I have when making a toy project from scratch in order to learn a technique (be it databases, blockchain, or deep learning). I'm always wondering if I'm allowed to use such algorithm or clone such github repo. Or if copy/pasting an auxiliary function is cheating or not.

To avoid such moral dilemmas I try to come up with projects that solve a new problem (which also comes with its own set of challenges). And then use all the means at my disposal.

As a bonus it also keeps me motivated, since it has a shot at being a profitable business idea.