I'm a follower of Cory Doctorow's anti-enshittification ideology (https://www.youtube.com/watch?v=FwkaS389W-g). Amazon is well-known for giving preferential treatment to its own products, while squeezing other sellers to pay for placement (Amazon ads).
If you want something more data-driven, see "Self-Preferencing at Amazon: Evidence from Search Rankings" (DOI 10.1257/pandp.20231068), but this one is about everyday products. I'd expect Roombas to get more blatant promos like Kindle, Fire, and Ring products get. For example, if I search for "doorbell" on Amazon, the very first thing I get is a huge promo for Blink products (an Amazon company), four results from random brands nobody heard of, and then another huge promo for Ring (Amazon brand).
Second, preferentially selling it on one retailer does not suddenly make all the competition go away. Amazon is not a retail monopoly or anywhere close to it despite Lina Khan's bullshit paper that went through some mental gymnastics to create that myth. If anything, the synergy with the retail storefront can reduce overhead and decrease prices to the consumer.
