I used to be like you. Still have dozens of hardware and software "prototypes" languishing in drawers and random directories.

I'm addressing the problem by making sketches on paper (yes, very old school) and writing rambling "design" documents before and during my work. That way, I am better able to focus and if I do abandon a project, I have some scraps from which to recollect my original thoughts should I attempt to restart a project after I have gained some applicable experience or knowledge by working on some other idea.

Yes, I was only today thinking I might reuse an old esp8266 thing I made and I thought - how did I even program that? And I would have been on Windows then, so how do I do it on Linux? I hope it will come back!