You could use lvdumpimg to grab the live view and scale it in another program.
Is this the screenshot button right next to the live view window?
The screenshot button saves an image of exactly what is displayed in the GUI.
lvdumpimg is a chdkptp cli command. It's similar to the screenshot button, but can pipe the output to external programs. Use help lvdumpimg for information. USAGE.TXT has some piping examples. But again, this would just let you save a screenshot and then enlarge it, for example by piping through imagemagick or something like.
It's possible the "digital teleconverter" setting will give you a magnified view
Where can I find this setting? Couldn't spot anything named like this neither on the camera menus, chdk and ptp
It's Canon menu option, under digital zoom. You can set 1.6x or 2x under "Digital zoom"
Unlike standard digital zoom, this is applied regardless of the optical zoom setting, hence the "teleconverter" description (for this camera, it looks like manual calls it "digital teleconverter", but the menu doesn't)
