Why does my apple watch series 7 41mm not show the keyboard when texting. Meanwhile apple has announced to have a keyboard

See this about sending a message, Send messages from Apple Watch - Apple Support and this extra about accessing the keyboard. If you don’t see the keyboard, swipe up from the bottom, then tap the Keyboard button.

You have Dictation already turned on, that is why the microphone icon is colored. Tap on it again to turn it off. After doing that, try swiping up and you should see the keyboard.

Try restarting your Watch.