Add at least two zeros to your number. Pixel phones can detect the top 11k songs while being offline (it used to be more). The fingerprint database for this is around 500 MB in size.

I think it is very easy to sneak a few (thousand) extra fingerprints in this database and do all kinds of tracking with it. All while the green microphone icon is disabled.

Now Playing only has to sample for a few seconds every few minutes when the phone is powered on for other reasons (like to participate in cellular check-ins). This is because a song is typically several minutes long and you only have to fingerprint for a few seconds. It doesn't matter which few seconds. It's not continuously listening, so it's not the same thing at all.

Song identification and speech-to-text are massively different algorithms.

How does it work? Bought my gf a Pixel 8a recently.

These conspiracy theories have been floating around since long before any of this became practical.