Amazon is of course not the be-all and end-all when it comes to selling physical products. There are countless physical stores out there, as well as many manufacturers that will offer affiliate programs direct to marketers.
You might find that if you take the time to look around for other products, you’re able to find something that is much more directly relevant to the topic of your site (and thereby more likely to sell).
To find these affiliate programs, just try typing in your niche and then “affiliate program” when searching on Google. You can also find plenty of lists online for the best affiliate programs in each industry.
Another option is to direct a manufacturer or seller that doesn’t offer an affiliate program… and then to ask them if they would consider creating one for you. If you manage to do this successfully, you can strike up an exclusive deal and potentially get a large commission too.
Of course, for this to work, you need to be able to demonstrate that you have the reach and the influence to make it worth their while.