My recommendation (n=1, ymmv) is to keep the job and find open source, non profit, or other "meaningful to you" work to do in your non working time. Maybe even ask for 10-20% time to do some of this work on work time, if your employer is open to it. This job sounds unique and hard to replace with something better, find the meaning elsewhere. Most jobs are not meaningful, they are a means to an end (getting paid).
Would you be happy if you landed somewhere much more challenging but with less work life balance and control over your working arrangements, leading you to regret leaving your current role? Ambition and desire to grow are important [1], but so is being mindful of the hedonic treadmill as it relates to work.
[1] https://en.wikipedia.org/wiki/Drive:_The_Surprising_Truth_Ab...
Thanks for the tips, thats what im actually very afraid of, is the work life balance, my current company is a heaven tbh