There's no option to freelance while on an H-1B visa and the options to work for another entity concurrently - that is, to get paid by another entity - are very limited and self-employment is generally prohibited. That being said, preliminary steps to create a business or to volunteer for a non-profit are allowed.
Really complicated and nuanced stuff unfortunately. What's clear is that one can incorporate, get office space, build a product, and even get funding and that one can't get paid cash for work done. Everything else in between is nuanced, such as generating revenues if not taking a draw or cut. I'd be happy to talk this through with you and anyone else but my general approach is that once the business is real (not a great definition, I know) and not just a hobby or side project, one needs to get work authorization.
My I-140 is approved and my wife has an EAD. Are there any restrictions that would prevent her from opening an LLC and getting paid for her freelance work through it?