If you got a job at a high-status tech company in California, you can get another job at a different tech company. It's like complaining you got into Harvard and other Ivy League schools wouldn't want you.
If you want to work on something different, you can only do that by getting a different job, either in the same company or at another one. If you stay where you are, you know you won't get what you want, so you need to make a move.
I have never, in my entire life, seen someone who is unhappy with their job somehow find happiness without changing jobs. And it's not good enough to find hobbies or devote time to family -- if you don't like your job, you don't like 1/3 of your waking hours and you should really do something about that. If the job is the source of unhappiness, staying in the job will perpetuate the problem.
Furthermore, the OP is in a very privileged position and has many options available, as does anyone else who works at a large California tech company.
> If the job is the source of unhappiness, staying in the job will perpetuate the problem.
There's a bit of a leap here -- you're made unhappy by your job, but it's harder to say how much of the cause is the job vs. you. The relevant question is really just whether taking your current mind and putting it in a different job will make everything better, or if the issue is, at least partially, how you're relating to your job.
I say this as someone who's had a string of jobs where I'm unhappy for ~similar reasons. Each was a bit different, but the consistent undertone of unhappiness makes me think that it might be higher leverage for me to examine my relationship with my job instead of just hoping over and over again. I suspect there's ways of thinking about my job that I'm "carrying" with me, and addressing those things will do more for my happiness.
Changing jobs is (likely) necessary but not sufficient. For example, if OP works a front-end job at Meta and switches to a front-end job at Google, that's unlikely to make them motivated. I don't think you're "missing the point", but I do feel that your answer is very incomplete.
If you want to work on something different, you can only do that by getting a different job, either in the same company or at another one. If you stay where you are, you know you won't get what you want, so you need to make a move.