Line a 9×9-inch baking dish with parchment paper (use a smaller pan if you prefer thicker treats).
Melt the 5 tbsp vegan butter in a large pot or Dutch oven over medium heat.
Add the vegan marshmallows and cook, stirring often, until the marshmallows are melted and the mixture is smooth and stirrable, about 5–6 minutes; remove the pan from the heat.
Stir in 1 tbsp non-dairy milk (or water), 1 tsp vanilla extract, and 1/4 tsp almond extract until combined.
Add 4 1/2 cups brown rice crisp cereal and 2 tablespoons of the 1/4 cup vegan sprinkles; stir until the cereal is evenly coated with the marshmallow mixture.
Transfer the mixture to the prepared baking dish, cover your palm with a small piece of parchment paper, and firmly press the crispies into an even layer. Sprinkle the remaining sprinkles over the surface and press them lightly into the treats using the parchment paper.
Cool the rice crispies at room temperature or in the refrigerator for about 1 hour, or until firm, before slicing.