From your objectives, I don’t think you want to learn computer science, you want to learn how to be a full stack software developer.
Learning certain aspects of computer science may certainly help you, but it’s by no means a prerequisite - and won’t help you to actually build things.
Learn the things you aim towards by doing and reading domain specific knowledge.
Computer Science is fascinating and wide, but if you're interested in reskilling into a new, professionally profitable sector, veering too much into the theoretical aspect can prove detrimental.
However, as you mention, your objectives will adjust the more you come to learn, so it's important to keep an open mind and read more widely than just the next necessary thing.
Just beware of ADD side-tracking you, and have clear road maos. (Speaking from personal experience there, I always have to keep a check on my direction during both study and work, lest I lose too much time without much benefit.)
Speaking of roadmaps to study, perhaps this site can provide an early guide, augmented by books and courses, for your chosen field:
And don't let your age deter you. People who love what they do are rare and priceless in any age range. If a company doesn't want to hire you due to your age, then that's probably a company you wouldn't enjoy working for anyway.