The idea of a side project needs a bit of reframing.
I used to think they needed to be this formal thing. I'd set up a Trello board, a Notion page, write a business plan in some cases.
But those projects ended up feeling too much like work for me to enjoy them, and I'd always end up ditching them as as result.
There's nothing wrong with ditching a side project, but ditching a side project that you invested "real world" expectations into feels kinda shitty.
After all, what's the point of a side project?
That answer is probably a little bit different for everyone; it could be something for your portfolio. It could be to test out a new technology or framework. It could be something that you're looking to make money from.
Or it could just be for fun.
No matter the case, setting expectations for the project is key. The expectations should align with the overall goal of the project.
Most side projects should come with the expectation that they will be abandoned; the only exceptions are side projects for a portfolio when trying to get hired.
Side projects you're looking to make money from are not side projects. They are another class of application altogether, and thinking of them as side projects is detrimental.
Design your side project around the reason you're making it, not around what the project actually is. If you're making a movie app so you can learn Svelte -- focus more on how you can push your limits with Svelte, and less trying to make the best movie app.
Don't be afraid to take your time and explore. Take detours and scenic routes. Make U-turns with abandon. Get lost.
This is the very essence of the side project.