Great work! Is it ok for commercial use?
> build upon the material
Is there clearly defined difference between "build upon the material" and "using the material as part of your project"? Commercial use in most cases involves not wanting to release your own project under CC BY-SA 4.0. Even though it's possible to combine both (commercial use and CC BY-SA 4.0 for your own product), it's highly unlikely.
If your 'use' is more than copy & paste, you've probably crossed the line into the 'remix, transform, or build upon the material' line and need to distribute your versions of these things under the same license.
This doesn't mean your entire product needs to be under the license, only the derivative part(s).