Can I start an LLC while having a pending Green Card/EAD application, and currently on H1B?

Starting and working in your own separate business while on H-1B status is a violation of that status. It is not legal for you to work and bill for the work when you obtain your EAD. I do note that illegal work will not adversely affect you in the adjudication of a marriage based green card application to a US citizen. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.