I have a forum post where I simply collect images of developer memes:
The summary below the introduction post says (in German):
Es gibt 84 Antworten mit einer geschätzten Lesezeit von 0 Minuten.
This translates to English as:
There are 84 replies with an estimated read time of 0 minutes.
In my opinion, it will take more than zero minutes to “read” (i.e. look at) the images.
My suggestion would be to have a minimum value of 1 (instead of 0) for the estimated reading time to cover edge cases like mine with actually zero text but only images.