I have self-published some content and both platforms. You summed up their pros/cons pretty well. One thing I have been trying lately is to have one title in Kindle Unlimited (so it's free, but Amazon-exclusive). The rest of my books are not exclusive. Those I also make available on Gumroad specifically listing them as DRM-free. I also turned some of my books into video courses (and vice versa). Gumroad has also enabled me to sell live workshops and private consulting.

Feel free to compare the two UIs and what's available at each:

https://amazon.com/author/mcallaghan

https://walkingriver.gumroad.com