From India! I have an I129 (Successful H1B lottery selection) with an old firm, but never got stamped an H1B in the past due to Covid.

Will this affect my visa approval in the future as I am working on a startup which will be incorporated in US?

Not at all.

NAL! From what I know, stamping is only required if you want to leave the country (US in your case) and come back.