Oatmilk ice cubes in coffee might work reasonably well.
I wonder if one could churn it a bit to make icecream?
Without a machine, you can take basically any liquid and freeze it. While in process you habe to babysit the fridge a bit and stir it every 15 minutes for some time, I’ve done it before, like granita style.
It doesnt hold though so only make enough to consume that day.