dessert ideas for Saturday night

Your dinner sounds great! I recently made the fudgesicles posted by Orangette (http://orangette.net/2014/08/and-fudgesicles/, from an Alton Brown recipe), using about half full-fat coconut milk and half soy milk (I used Organic Valley, "original" flavor) instead of the milk and cream and they were really great -- no soy flavor, and very subtle coconut flavor. I think any mixture of non-dairy milks you like with a similar fat content would work well.
A friend of mine also recently made granitas from sweet vermouth and from sherry (two separate ones) that I think were just vermouth or sherry, stirred while freezing. They were delicious and refreshing.

Not entirely no-dairy, but how about aargersi's Big Kid Hot Day S'mores? https://food52.com/recipes/36979-big-kid-hot-day-s-mores

Here's an idea inspired by your near neighbors in SW Louisiana https://food52.com/recipes/23376-sorbet-jolie-blonde-joli-blon
Take advantage of the fact that peaches are terrific right now,

NYT cooking has a watermelon sorbet that looks really good. I'm in Texas too, I'm really into making sorbets this summer. NYT posted the recipe on Facebook today.

NYT cooking has a watermelon sorbet that looks really good. I'm in Texas too, I'm really into making sorbets this summer. NYT posted the recipe on Facebook today.

if you want a drink read this: https://food52.com/blog/17423-how-to-make-frose-without-a-blender-at-the-beach
Other option, make a fruit salad, grill some watermelon slices, pineapple rings, you can add the cherries and any other fruit available., grapes ,strawberries etc... sprinkle it all with some Cointreau or Chambord liqueur, have some whipped cream on the side.

Chocolate sorbet sounds good! Do you have a favorite recipe?

Maple butter tarts are yummy and can be made with margarine
instead of butter and they can be frozen ahead of time!

Coffee Granita? Chocolate sorbet? Margarita Popsicles ?

Don't know seasonality of avocado in Texas, but if available and you like them, consider chocolate-avocado mousse...easy, delicious, dairy-free. basic ingredients for six include 1 cup each cocoa powder and maple syrup, 3 ripe avocados, small amounts vanilla & coconut butter. Garnish with mint & berries in season.
Can't find the exact recipe now to link to, but there are many out there.
Also other avocado-based desserts, and other paleo desserts...many to choose from.