Really liking Boost for Lemmy, but missing this feature that we had in Joey. You could long hold any thumbnail, and it would display the image/gif full screen until you let go. It was a great way to “peek” at images/gifs without always tapping, swiping back, repeat. It even worked on link type content, displaying full screen whatever the main image was for the article.
Why would one preclude the other? Hold if you want to briefly view, tap if you want to see it without your finger in the way.