I don't think it's possible to work as a software engineer full time and have enough mental energy to do meaningful work on your own projects in your spare time.
It's been a few months and I do not miss coding full time one bit, hell even no longer being involved deeply in tech is a breath of fresh air.
I've had previous management experience (CTO in small start up, Lead Dev ...) so I managed to leverage that during my interview process, then it was mostly showing I was really interested in growing a product and see it succeed.
Software development, for whatever reason, directly spends "spoons" (in the sense of https://butyoudontlooksick.com/articles/written-by-christine...) at a high rate.
Because of this, it's hard to do much else that requires willpower after putting in a day's work as a programmer. You can do habitual things just fine; or procrastinative things. But, outside of those two activity-classes, it's hard to even do the most enjoyable of things—like, for example, watching a serious, dramatic movie—because you won't get anything out of such activities if you don't invest some emotional energy into them, and you've just plum run out.
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In a more technical sense, it's my understanding that the activity of programming somehow "uses up" a lot of dopamine, and so gradually depletes one's available store of dopamine over the course of the day in much the same way that stress, cold environments, and surprising loud noises are known to.
Thus, a neurotypical person who spends eight hours programming in a day, will end up effectively equivalent in behavior/mentality to a person with ADHD for the rest of the day, until they can sleep it off and recover.
(This means you could probably restore your "spoons" by taking ADHD medication just after leaving work... but that seems ill-advised, for multiple reasons.)