There is no Translate in Action Button on my iPhone

I have had the same issue but I realized that it needs the translate app from apple to be installed on your phone... After installing the app the shortcut appeared in the action button setting...

This is the app you should have installed:

https://apps.apple.com/ie/app/translate/id1514844618

Update your device. This is only available on the latest version of iOS.

I think it is. Make sure you follow the instructions here. Use and customize the Action button on iPhone 15 Pro and iPhone 15 Pro Max - Apple Support

Me too. I'm updated to the latest and it's not there. Apple translate has been installed for a while but it's not available when you swipe through the action options.