Lemmy does allow images. Just seems like they're attached some kind of different way. Now that I'm on desktop I can open that link on its own instance. And it's actually a little aggravating, the pictures are shown enlarged by default, with no way (I can find) to collapse them? But that's probably just the default UI or config for that instance.
I probably might open a Piefed account someday. One of those things I'd like to get around to, that I'm not in any hurry for.