Your boss may not let you work on it but there's no reason to not work on it outside the job for 5-10 hours a week, just for kicks. Those kicks might be enough to keep the day job more bearable.
If at the end of the day, putting in 5-10 hours a week extra out of your own time for it is considered too much, then accept that you also see your work as just a job.
The OP himself reckons the hobby is fine. It's the job that sucks. Sure, you can take some quality programming time outside your job, and the OP does exactly that, but your day job is still taking a huge chunk off your life.
When a job sucks, the solution hardly lies in what you do in your spare time. First, I would try to improve the job, or enjoy it, or quit it, or annihilate it (we're programmers, annihilating jobs is what we do). And if all that fails or otherwise isn't worth my efforts, then I will give up and learn to love my spare time.
When someone is complaining their job sucks, my first reflex isn't to tell them to man up, cheer up, or give up. It's not helping. instead, I ask myself what could be done about it.
Work normal hours for your job then anything extra pushing your skills in areas you find interesting. This can be on tangentially related work tasks or research or skills.
If you find your interests lead away from your job, then that is a path to skilling up for a more appropriate job.
If you think it sucks you have to work so long and hard to find and/or get those interesting jobs it does .
But it's because other people are willing to do this and will get the interesting jobs leaving the boring ones to those that don't.
Learning a useful tool at home related to work pays off.
For a web front end task job that doesn't have JQuery 5-10 hours in it could save so many hours at work after introduction you may look like a hero and win you more paid at work research time.
Prove you are worth research time to your employer.
Your boss may not let you work on it but there's no reason to not work on it outside the job for 5-10 hours a week, just for kicks. Those kicks might be enough to keep the day job more bearable.
If at the end of the day, putting in 5-10 hours a week extra out of your own time for it is considered too much, then accept that you also see your work as just a job.