It doesn't matter if it's already been done.
It doesn't matter if it has absolutely no practical purpose.
It doesn't matter if no one but you finds it impressive.
It doesn't matter if you know it will fail.
In a project, every rabbit hole, every decision, ever success and every mistake matters - you just never know when it matters. Some projects come and go and seem to leave only a vague memory of a temporary distraction from something else. Others move forward as a giant piece of know-how that accelerates part of a later idea. Whether you frame a project as an escape, a challenge, a display, a gesture, or any combination of those, it will always be worth your time.
We need to constantly be learning how to learn, pushing our understanding of the world around us. As people who identify as engineers, as builders, as "problem solvers", we develop this understanding by creating solutions that interact with our environment. In that mindset, every project is an experiment that gives us that many more data points to inform later experiments.
We need to constantly be learning about others and ourselves, challenging our own bias and driving our tendencies towards empathy and understanding rather than fear. This includes empathy for yourself - you will fail. A lot. Beating the shit out of yourself for the discrepancy between your 'ideal' you and 'real' you has a tendency to bleed out into how you treat others. It's important too to see the inverse of this in prickly people.
I've always struggled with the above. I have trouble giving myself the leeway to just take a break - to sit down and watch all of Forrest Gump on a Tuesday night and not think right after "Wow, I just wasted all that time". I've needed to push myself to actually understand the environment I'm building things for, and it's damn hard. Most importantly, learning about myself and what motivates me is likely the biggest challenge of all. Turns out there are many layers to forgiving yourself for failures of the past, and for the longest time, any bit of success and good was instantly tainted as contrition for those failures. It should be obvious that I'm no expert on mental health, optimal worldviews, or even most disciplines of engineering... But I have seen 25+ years of building things provide me with a constant purpose and drive, even through remarkably dark times.
So go build stuff. Let it be whatever you need it to be.