Pixelmator is made in a country that's designated "flawed democracy" on the democracy index, so I was always hesitant to buy or trust it. This purchase by Apple may help a bit.
Even if it was available on the App Store, that wouldn't suffice for me. I would get it only if it was available as a "channel" in the Apple TV app. I just subscribed to a channel in the Apple TV app last week. Any company that fights privacy, convenience, and ease of use won't get my business.