However, getting rid of the /photos prefix would be a terrible improvement.
Having the /{username} at the root of the routing logic means that every URL should either query the user database for a match or use /{username} as a catch-all fallback if no other patterns match. But this makes resolving real 404 pages much more expensive.
I've been using this technique on my cat for a long time. For example, when something scares her, like fireworks in the street, she looks at me with her eyes wide open. In response, I slowly narrowing my eyes to let her know that I am relaxed and she immediately calms down.
I was using Django Rest Framework for many years (and still using) but I can't recommend it to anybody. I would recommend FastAPI which is more straightforward and has modern features and not abandoned (like DRF is).
Having the /{username} at the root of the routing logic means that every URL should either query the user database for a match or use /{username} as a catch-all fallback if no other patterns match. But this makes resolving real 404 pages much more expensive.