We recently bought a cellular Apple Watch for our child and set it as a family member watch with a Truphone plan.
It seems we can’t install Spotify on it as it needs the iPhone companion app.
We have an old iPhone 5 so we may need to sync the Apple Watch using his iiCloud account.
What’s a decent esim plan nowadays?
No idea if an iPhone 5 would still work nowadays but you certainly don't need an esim (which it doesn't support anyway). WiFi-only connection should be sufficient to setup.
https://support.spotify.com/au/article/spotify-on-apple-watc…