Easiest way to listen to a text?

Push the enter button on the left handlebar if the text just came in. The one in the center of the controls. Text will be read to you. And then you can respond. One button.

I thought I tried that but maybe I was too slow or had a mis-hit

Yeah it does not give you a lot of time.

I'm guessing Apple Carplay is similar to Android Auto in that if you push and hold (until you hear the beep) the phone/voice button, it activates Siri/Google Assistant. Then you can just say "read text." After the text is read to you, it will ask you if you'd like to respond. Every subsequent action doesn't require any other button pushing, so that single press and hold allows you to listen to multiple texts and respond with your voice.

More than one correct answer above!

One button press only. Hey Siri, read my text.