Yes!
Storytell is very "side project" friendly. We believe that side projects unlock our creativity that then enables us to do better work at Storytell (bringing new technologies into the company, new approaches, etc)
California is also a very "side project" friendly state (here's the relevant labor code), which means that no employer can claim ownership over what you do in your free time, regardless of what the employment contract states. This is why our CIIA (the company invention assignment document you sign when you start) specifically scopes inventions to "company inventions". It's also why we specifically call out applicable state law limiting invention assignment in our CIIA.
So hopefully you can tell that we're fully supportive of you learning, growing and experimenting on your own time -- your manager's main concern is only going to be you & them doing great work at Storytell to build the future together.
You can also learn about our "Future Founder Promise" at the bottom of the Storytell Careers page:
Here's a screenshot: