This is just my tuppence worth, but I have changed careers twice now and have a little experience of that, although not specifically in the areas you are considering. I will say I am also late diagnosed neurodiverse and this has contributed to my jumping around career wise.
Do some volunteering/work experience in the area you are interested in before you do anything else. I nearly jumped from nursing to a PGCE for English. I got a little bank TA under my belt and hated working in the two schools I was in, I wasn't the right fit, it wasn't for me, I knew within a couple of months. That was a well avoided mistake, because everything I thought I was getting myself into was wrong.
If you're looking for meaning and to make a difference, don't assume that your career is the only place to do that. What if you compressed your hours into a 4 day week and used the fifth day to volunteer in the areas you are interested in. You keep your salary/flexibility and you get to make a difference. Explore the ways things might fit together by looking at your life as a whole, rather than a black and white of what job you do.
Don't underestimate how it will feel going from a well paid manager role to a junior position. You will likely either take on more than they are paying you for, or you will have to make big adjustments due to not having influence or much of a voice. It's a bit of a jolt. If you do it in a completely new area, you will simultaneously be experienced on one hand and inexperienced on the other. It's a tricky combination.
Your ability to genuinely change something will be quite limited. Think of work as it is now and how much influence you have there. It's much the same working in health, social work or charities. You can do good, don't get me wrong, but you're not going to change the world, the country, or even the team you're in. That's a recipe for rapid burnout.
All that said, if you've thought of all that or read through that and thought, I'm still going to do it, then go for it! It's not easy to make these changes, but it does make for an interesting life and at least you'll then know you tried. I'd start with a toe in the water through volunteering or an intro course (rather than full on into a degree or masters) and see how it feels.