Once the weather warms up we know that the grandkids don’t need scarves, mittens, or cosy sweaters.
But they may like a vest-

Sweetness Vest

Provence Vest
Just think how cute the little ones will be in a vest- a little dressed up for a special occasion, but they can still run or crawl.
The top one is knit out of Sweetness, a sport weight variegated yarn. The lower one is knit in Provence, the old standby worsted weight cotton from Classic Elite. Both are machine washable, kid friendly yarns, so when the ice cream hits the hand knit it’s not a disaster!
Both patterns are commercial, the Sweetness from a booklet full of patterns for that yarn, and the Provence from Minnowknits.