I use a self-hosted wiki to keep records of more formal things, such as project dev documentation, lists of project ideas, etc.
It's here if you want to check it out: https://sandbox-mvp.vercel.app/
You should be getting advice from those who have needs that this sort of product solves.
If so, keep at it.
Or use it to make something else.
If you want to make stuff, make stuff. Don't worry about it being useful. Not knowing is a good reason to make something. The next thing you make will benefit from what you learn. From the experience.
Ideas that you aren't motivated to work on, aren't worth having. Taking notes isn't starting. Good luck.
But then I really understand that building things make you better at building useful things that people would want to pay for. Thanks!
Probably not. If you have a day job, you can make for the sake of making.