Would one use holy basil to make pesto sauce? Are there other culinary uses

If you pinch off the basil flowers as they start to grow, the plant will produce more leaves. (Yes, this is a horticultural answer, but it will help you make more yummy dishes with the leaves.)

Generally, there is no reason not to use it. However, I'm hard pressed to think of a good place, generally because good cooking prefers other, stronger flavored liquids instead of water.

An application where you can have the flavor on its own would be making ayran or a lassi. I think it would be an improvement over plain-water-ayran.

For other uses, just substitute plain water to get a slight nutty hint. I like to pair rice with nuts, so you could use it instead of pure water to cook rice. Or add it to a pot of stock you are making - with a complex stock of a meat and several vegetables, it will be too subtle a taste to register consciously, but will enrich the flavor as a whole. For a simpler stock (e.g. just chicken with classic mirepoix) the taste of almonds can get too strong, depending on the quantity you use.