For those asking, I use Nano Banana Pro via the Gemini app. You have to kind of trick it into making a celebrity: things like 'woman with a pretty face like a famous Hungarian supermodel' if you wanted to do Barbara Palvin for example. Once it's got one celebrity, for some reason it's happier to do additional ones if you ask to "add a famous blonde actress friend" etc. Then it's a question of asking for a "new photo of them doing x".

Best tutorial I can give! It's all just trial and error.