I have a company that will have many saas products under it . For now if I ask investment, do I have to offer equity of company just for that one product? Is there a way I can offer equity of just that one product?
If you want equity for just one product, then you should consider putting that product into a new company.
You can offer fractional ownership of just one product, but the complexity and liability issues are reasons why people don't do it that way. Putting the product into a new entity, which needs capital, is the effective way of doing the same thing.