How to add non iPhone messages to apple messages
I used to get all my text messages in apple messages. Now only the iPhone users show up.
MacBook Pro 15″, macOS 12.6
Did you one have an iPhone but no longer? To texts all users from a Mac requires you have an iPhone with text forwarding turned on and linked to your Mac.
Forward SMS/MMS text messages from your iPhone to your Mac or iPad - Apple Support
If you have an iPhone, maybe text forwarding is off or does not include your Mac. The above article shows how to connect.