The soundtracks for all the main Half-Life games, including the first chapter of Half-Life: Alyx, are available on Spotify now.
You can head to Half-Life's official site to find links for each soundtrack, including options to download them on Steam or find them on a variety of music services. Each game's full soundtrack is up for downloading or streaming except for Half-Life: Alyx, which will be uploaded in smaller pieces:
"The Half-Life Alyx Soundtrack will be released in a chronological fashion following the chapters of the game. While chapters are being published, the soundtrack will be available for streaming on Spotify and Apple Music, and for download on Steam Music. Once the entire soundtrack has been released, it will become available on all major music streaming and download platforms."
Chapter 1 of the Alyx soundtrack, titled "Entanglement", has a 21 minute run time all by itself. If you're a Half-Life fan but haven't had a chance to try Alyx yet, you can at least enjoy the music. As long as you don't mind, um, musical spoilers? The ambient vibes and track titles might give you some idea of what goes on in the game, admittedly.
Even if you aren't ready to listen to the Half-Life: Alyx soundtrack yet, you can enjoy the music from the previous games. Listening to "Klaxon Beat" from the first game or "Hazardous Environments" from the second still gets me hyped up to put on the HEV suit and beat zombies to death with a crowbar every time.
Valve has said that the success of Half-Life: Alyx will determine whether the next game is also in VR.