I imagine baby pigeons look very similar to other birds when hatched, naked as a jay bird.
I probably have less experience but from that limited amount I can say they actually don't look like other birds. My scant experience is that they have a really nobbly, huge (in relation to their size) disturbing beak and feathers that just.... defy description. To say they're "patchy" would be kind.
I really like pigeons (people call them rats with wings but I've also had pet rats so I never viewed that as a pejorative) and I also subscribe to the notion that baby animals are nearly universally cute. But baby pigeons are.... not. I love the adults but the babies really are kind of horrifying. (Sorry, Iain Utah)