Digital Agency as a part of e-commerce website?

I once saw someone here posted a link where some guys had a Digital Marketing agency website and posted content reviewing cameras and stuff from Amazon which ranked well and made them some extra money, not sure how much.

So I was wondering would it be possible to start an agency as a part of e-commerce site which could be used as a showcase. Has anyone tried or seen something similar? What do you think would that work? Thanks.

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