just like I'd expect someone who likes Alexa to use all their devices, and same with Google and Android.
Not really, by far the majority of people I know who have an android phone are using Amazon echo over Google home. I know more that use the Home or Echo over Homepod. Those that use the Echo have an iPad over a Fire and so on.
People use what works for them, regardless of who makes it. Those that focus only on Apple do so because it's so closely connected as much if not more than their devices being the best.