Is there a +64 number to which I can send an SMS, that will reply with a SMS?

My situation is I have poor cellular service at home.
I have an iPhone 13, with a 2Degrees SIM and a Rocket Mobile eSIM. Calling over Wifi is enabled, and works on both connections. I have verified this using Shawn Ewing's very handy test phone number. Wifi calling works on both connections, when in Aeroplane mode, with Wifi connected (i.e. no cellular connection)

However, I cannot get SMS messages to send, specifically using the eSIM number, and I don't know whether they are being received by me, or not.

Hopefully there's an automated service I can use rather than annoying someone with multiple texts back and forth and asking for replies etc.

Cheers,
Joseph