Can the Apple Watch receive texts from android phones without a cellular service connected? As in the watch only has GPS not cellular.

The Apple Watch depends on the iPhone to receive SMS/MMS TEXT messages, as the LTE radio in the Apple Watch cannot do SMS/MMS, and of course the GPS Only Apple Watch does not have an LTE radio.

Use your Apple Watch without your iPhone nearby - Apple Support

See the #2 footnote

2. To receive SMS, MMS, or push notifications from third-party apps on your cellular Apple Watch, your paired iPhone must be powered on and connected to Wi-Fi or cellular, but it doesn't need to be nearby. You also need to be signed in to iMessage on your iPhone to use Messages on your watch.

The GPS Only Apple Watch just uses the iPhone for any cellular activities, including SMS/MMS TEXT messages. And yes, I've done Green Bubble TEXTing with an Android user.

AMSAMS59 wrote:

So if I had the gps version and left my phone at home could I send messages to android users with the watch?

Most likely not.

Your Apple Watch would have to join a local WiFi network, then it could use Apple's Messages to connect with the iPhone and the iPhone could then send/receive the SMS/MMS messages.

But it is rare that when you are out and about, that your Apple Watch would join a WiFi network.

So for the most part, leaving your iPhone at home, means your Apple Watch will track your exercise, tell you the time, and maybe a few other services that do not require access to the Internet.

I've been using my Series 4 GPS only for the past 5 and a quarter years. Because I almost never leave my iPhone behind, my GPS only Apple Watch has done everything my Wife's cellular Apple Watch does.