I’ve completely switched to eBay for most purchases. Yes they are also a giant company, but more focused on used goods and small sellers.
It’s often cheaper than Amazon too, and most major brands have their own official store page. Certified refurbished items come with a 1 or 2 year warranty. I always buy used if it’s available, and from the smallest seller, so it recirculates products and helps everyday people who are trying to declutter.
Selling fees have gone up over the years (about 13%, but still much lower than Amazon). And eBay does a lot more advertising for new products now, so I’m not so hopeful long-term. If there was a smaller company offering the same benefits I would switch, but so far nothing comes close (in the US at least).