Streaming Your Own Music
Amazon Echo used to let you upload 250 of your own music files to the cloud, or up to 250,000 if you paid $25/year.
HomePod lets you upload 100,000 songs to iTunes Match for $25/year. It cannot initiate streaming from your Mac, even if you use Home Sharing.
Google Home Max lets you upload 50,000 songs for free.
I still use iTunes to sync music to my iPhone, like an animal, and stream from the phone to a Logitech Bluetooth speaker. So I can use Siri to play my own music for free. Right now, I use my own phone for this, but the downside is that as I move around there can be interference or I can get totally out of range. Also, my iPhone SE is full, so much of my music doesn’t fit on it. It might be better to dedicate an old iOS device as a stationary music controller, but that would make controlling it less convenient.
The other option, which I’ve used in the past, is to stream from iTunes on my Mac to the Bluetooth speaker. This can be controlled from the Remote app on my phone, but that is slower and less nice than Cesium and doesn’t work with Siri.
I didn't know Amazon is shutting down its music storage service. I didn't use it, but I'm sad that there's less competition out there.
I rely on streaming my own music too. As buggy as iTunes is, the combo of iTunes/iOS Music app/syncing between the two is still something I can't replace. I keep hoping for improvements to iTunes Match so that I can upload my files instead of trusting its flaky matching service. But I guess there's not much business in cloud music storage when streaming is taking over?