I've started fairly enough projects in my life. Most remained in the form of an idea. Some of them reached the prototype stage. And released quite a bit.
The craving for creation has not disappeared over the years. I gained the ability to value my time instead.
In the end, I was able to develop a checklist for assessing the attractiveness of a pet project.
The project should be useful for you personally and you will use it on a regular basis
Technologies useful in your career
Even if the product does not take off, you will master or learn better the next technology
Interesting tech stack
In your main job, you can sometimes put up with tools that don't quite suit you. But here is a hobby, the stack should fit you.
It is immediately clear how to make money
Let the audience be limited or the average check low. But we do not know what will lead to success, so we will simply achieve it by the number of iterations.
Tangible and moderate deadlines
The project can be broken down into PoC and MVP. MVP is short, no longer than 3-4 months of your free time.
Using this approach, even if the project does not go live, you will enjoy the process and acquire a new skill.
Good luck with your projects!