Adding non niche related reviews to Amazon Site?

So basically I made an Amazon affiliate site in a specific niche, but Im running out of content and reviews to write. I am currently only making on average of about $20 a month, so after hosting fees only like $10 profit a month. My niche is basically a specific 1 item that is in the more broader man cave niche, and my domain contains my main product keyword. My reviews are mostly ranking on page 1 for my keywords. So my question is can I start adding reviews of other products in my broader niche like Smokers, Grills, Brewing Supplies and such, and will they still have a chance or ranking in google. Or should I just give up on the site and try to sell? And Start over with a better niche?

So no opinions on this matter?

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