Worth noting JSS is the default usage in material-ui's component library. Also worth noting, that if you have separate designers, that staying closer to (s)css may be a better option.
It looks like themes are the only way to do this... you can try saving them into your global settings file manually. Been a while since I even considered it.
In general, I tend to favor the mdi packages for icons, it's based on the google icons, but extended with thousands more community based icons.
https://www.npmjs.com/package/@mdi/font
Usually best to write/export a dynamic method that will have a global reference and return the global or dynamically loaded module, assigning the global after loading.
Note: this is expressly for EcmaScript Modules (esm).
It's an interesting approach, given the transition of decorators in ecma, I'd mostly stopped using them. Would be curious to see how this works for Redux... assuming some type of middleware to work in conjunction.