Kagifeedback could certainly make images more accessible (on mobile).
A trick I use on desktop is: right-click image > "Open image in new tab"
I just tried the equivalent on Android: long tap image > "Open image in new tab"
- The image in the new tab can be zoomed using two finger gestures
(A little more difficult on iOS: long tap > copy; open the copied URL in a new browser tab)
On iOS: long tap image > Show Text
- The image can be zoomed with two finger gestures.