There is no direct, image link support in Pages.
I have demonstrated for years in this community how to insert a text box and fill it with "#" or "*" characters at a larger font setting. The entire contents of the Text box are then selected, one applies a link to that selection, and then from a Style panel, sets the opacity to 0. Then it is a matter of overlaying the image with the slightly smaller Text box, and grouping them from the Arrange panel. This is best used when exported to PDF, though possible in an EPUB with more involved post-processing of that format.
A Pages text box when exported to EPUB loses its transparency, and the rows of linked characters appear. As I mentioned, this can be fixed with an EPUB editor (e.g. Sigil), and by editing the principle HTML page. There, one finds that the Pages Text box is now a DIV container full of page <p> tags containing anchored rows of text. One only needs to add an opacity:0.0; style element to the DIV inline style to make the entire contents of the DIV transparent — the way it was intended. Saving the EPUB shows a linked image in Apple Books, with no overlayed artifacts, and though unlike a PDF, Books challenges you for permission to complete the link.