from this link I understand a little better
if I dont subscribe to Apple Music and iTunes Match, which is my case, I lose the Siri capability to play song for me but I can still do everything I need . every Mac that can access airplay 1 can be use, we can even play flac
from link
https://www.imore.com/how-homepod-works-apple-music-itunes-match-icloud-music-li brary-airplay-and-flac-files#nomusic
___________________________________________________________________________
If you buy HomePod and do not have a subscription to either of Apple's streaming services — Apple Music or iTunes Match — you'll be able to use the following audio-based features.
You can ask Siri to play the following:
Any podcast or episode from Apple's iTunes podcast directory
The news
Any song, album, or audiobook purchased through your Apple ID associated
with the device (which you can change at any time in the Home app)
Beats 1 and other live radio stations
You'll also be able to use Siri to play, pause, skip songs, and the like. And all the other Siri features advertised (HomeKit, timers, weather, traffic, etc) work, too.
Even though HomePod doesn't ship with AirPlay 2, it can still receive audio from any device that can AirPlay. That includes your Macs, Apple TV, iPhones, and iPads, along with any third-party apps that support the feature (including work-arounds for Android and things like AirSonos).
I want to reiterate, because I've seen a number of people passing around conflicting information: You can stream any audio (including anything from your iTunes library on your Mac) to HomePod via the original AirPlay protocol.
When AirPlay 2 launches, you'll be able to stream that audio to multiple AirPlay-compatible speakers, but the AirPlay 2 protocol is not required to stream audio from your Mac or other sources.
What does this all mean in practice if you're not an Apple Music subscriber? Essentially, you'll just have to use one of your devices to AirPlay content to your HomePod instead of using Siri to request it. You'll miss out on a lot of the Siri-specific music features, but it's not the end of the world if you're primarily interested in HomePod as a speaker and for its better privacy implementations than other smart speakers.