XS road bikes with full size wheels are always just kind of awkward. Salsa makes a 24 inch wheel drop bar Journeyman. Surly has some of their XS road bikes with small wheel options.
I know you have a gravel bike in mind. You might consider a premium kids hybrid bike like a Woom 5 or 6. They are very light, not junky and use gravel-ish tire width.
Last edited by Darth Lefty; 05-16-22 at 12:28 AM.