oh, haven't figured out how to extract the pictures from the dlsite browser viewer?
the way I found it is a hassle but it's doable from a computer using firefox open the work with the viewer, if it displays 2 pages side to side, click on the gear on top and disable the display spread-page option to have them one by one
inspect the image, that'll send you to a <canvas> tag right click on it in the inspecter -> copy -> image as data-URL open a file on your computer with a .html extension make an img tag in it like so <img src="[paste data-url here]"/> add as many img tags in your file as you have images to copy from the viewer save the file and open it in browser, now you can save them as files on your computer