This exact image, probably of a developer's dogs, is a collectable treasure in Pikmin 4

It's in a picture frame and called the "Buddy Display" 🥰

Here are various character's in-game thoughts on this treasure:

“This device not only stores but also displays images from the distant past. And there's something about the image frozen on the screen now. The two friendly creatures there are...familiar...somehow. Try as I might, I can't quite put my finger on it.”

“What mysterious and fluffy creatures. I can't find evidence of them in any of the existing creature databases, but there's something familiar about them. It's almost as if I've met them before... I guess I'll chalk it up to an ancient memory that's been imprinted on my genome.”

“I'd like to take a ride on the back of either of these creatures.”