Add text to a photo with iPhone keyboard

I'm making my first attempt to mark up a photo with text. I got into the markup tool and clicked the "Text" icon, which brought up the toolbar below the photo. I see a box where my text will appear, and I can see where I can change the font, font size, and color. What I don't see is a keyboard. Surely I'm not limited to using an Apple Pencil or my fingertip! Where's the keyboard?

Apple's little help article on markup (Use Markup on your iPhone, iPad, or iPod touch - Apple Support) is of little help.