Seems like the professional artists websites have the images separate on say one page. Once you click on that image it goes not to a letterbox but a gallery with the start being the picture that you clicked on the image. From there you can open a letterbox or go to the next image. Is this anywhere possible in Sparkle?
Not currently possible unfortunately.
Helas, I cannot wait until some of that functionality is possible in Sparkle. In the meantime I build something like this (manual work) is this something you mean ? Click in the top menu either on “Foto’s” or “Video’s”. In the Foto’s page I used different gallery-styles, to experiment with.