Do the commissions you make selling books through Amazon/Bookshop.org impact publishers or authors?

No, this has no impact on authors, publishers, or their revenue. 

Amazon and Bookshop.org give us a small percentage of any book sold through our website. It helps us to fund the website. And this has zero impact on authors or publishers and is just an advertising fee that Amazon/Bookshop.org pay us (called an affiliate program).