I'm also a fullstack developer.

There's a ton of questions here we can't answer for you. Some places you might start:

1. Start living frugally. Most people "live up to their income". This creates the impression that you're trapped, because you have to keep making the same amount of money or more. But this isn't the case. If you're making an average fullstack developer salary you can live on a fraction of your income. That can give you a lot of options such as "take a job that pays less" or "take some unpaid time off" or in the long run simply "retire early".

2. In a similar vein, eliminate debt and any other obligatory monthly expenses you can. This especially includes housing expenses--if you can downsize to own a home outright, do that. Not having regular expenses means you don't need regular income.

3. Share your feelings with any relevant stakeholders in your life: your spouse if you're married, your kids. Any solutions you look for are going to have to include them so it makes sense to start collaborating with them on those solutions. Hint: Your boss isn't one of these people, even if they legitimately are your friend.

4. Talk to a therapist. Just as it's valuable to have input from stakeholders in your life, it's valuable to have input from outsiders who have no stake in what you do and can look at this more objectively. Additionally, if you're like me, you spent a lot of time learning about computers and science and math and other academic pursuits, and never spent any time intentionally learning emotional skills. In the same way you might seek a class organized by a teacher to learn a new programming language, you can seek out someone to learn emotional skills.

5. Try new things. Things outside your career and outside of your comfort zone. Things that are the opposite of what you're doing that you don't like--things that are unprofitable, physical, or outdoors. I think part of the problem with a lot of software folks is that they get stuck doing what they don't want because they never figure out what they do want. It may be that you don't know what you want to do because you haven't tried it yet.

I think pretty fundamentally, a lot of us got into this career because we thought it would make us happy. At this point, I simply don't believe happiness comes from a job for most people. Some people enjoy what they do for a living, but fundamentally it's the thing they're doing, not the fact that it's their job, that brings them happiness.

For me what the last few years have looked like is: stopping drinking, getting medicated for ADHD in a way that's geared toward making my life better not making me more productive (meaning, non-stimulant), diving deep into rock climbing which gets me physically active and outdoors, moving into a van (which is paid off) to remove all housing expenses, and doing fullstack development freelance so I have ample chances to take unpaid time off. I make less money, but I make more than I need. I'm working on some esoteric programming projects that have gotten me back to the things I liked about programming in the first place. I don't feel like I'm where I want to be, but at this point that feels hopeful, like I have goals I'm making progress toward.

Your answer probably doesn't look like mine, but don't be afraid to dream of something equally as outlandish-sounding if it sounds appealing; the reasons you feel like you can't do something may be less critical than you think.