It's 2023, and if you ever have any question regarding text, the answer is try ChatGPT first.
That includes not only poetry and source code, but things like CSV, JSON, and XML. It's wild what you can do.
UPDATE: 16-Jul-2023 - With the release of ChatGPT's Code Interpreter you can generate CSV much more creatively;
Luke Wilson pointed out that you can also have ChatGPT generate dummy image fields, and gave this example.
For purely random images;
Use Unsplash's Random Image API with a unique seed parameter for each image url to ensure different images are returned.
For typed images, try specifying specific URL constructions you want ChatGPT to use;
https://source.unsplash.com/featured/?nature
For specifically-sized and typed images;
https://source.unsplash.com/600x400/?mr-potato
https://placehold.co/
https://placehold.co/600x400
https://placehold.co/600x400/000000/FFFFFF
https://placehold.co/300x300/purple/white?text=A
https://placehold.co/600x400/orange/white
https://placehold.co/600x400?text=Hello+World
Even video;
https://placehold.co/3840x2160.mp4?text=Hello+World
https://loremipsum.io/21-of-the-best-placeholder-image-generators/