The title, "More-ish," gives the key: this is about wanting more even when you already have plenty. The speaker's hands are full, yet they still manage to "find / something more." There's a small, almost playful greed in that, the feeling of being unable to stop reaching.
The second pair of lines turns this into an old saying. We say someone's eyes are bigger than their stomach when they take more than they can handle. Here, the eyes are "bigger" than something unnamed, and then the poem shifts to "the light in my eyes." That change softens the idea. The appetite doesn't feel like a fault anymore. It feels like delight, a brightness that comes from wanting and finding.
The mood is light, curious, and quietly joyful. The short lines and missing punctuation make the poem feel quick and breathless, as if the speaker is mid-reach. The poem seems to suggest that wanting more can be a sign of being alive to the world.