i would say that 'comfy' can be applied to nearly anything (whether it be clothing, an image, a room, a color, a food, a sound, or even smells) as long as it brings you a sense of satisfaction without the assistance of any external actions/forces. if i have a particularly comfy hoodie, i feel comfortable just by wearing it, regardless of my surrounds or what i may be doing. if there's an image that i deem comfy, it's because just looking at it brings me a sense of contentment; and for however long i admire it, any external worries or stresses seemingly melt away.
it really is an elusive term and i think that in itself brings a sense of /comf/ort, it's an incredibly subjective/personal term, and for that i love it.