Welcome to TFP! If you do a search here on the forum, you'll see many owners who have used PVC adapters to create a simple fountain from a return jet. There is no real right/wrong way as long as it connects to the return fitting and you like the way it sprays. Keep in mind a fountain can cause aeration in the water which may also increase pH over time. Cooling our TX pools this time of year can be challenging.. I have chosen to run a simple hand sprayer on certain mornings (early) which seems to help knock the temp down a couple notches. I figure I have to add water every 2-3 days from evaporation anyways, so why not do it this way?
Your options seem limited, do you even have an eye socket you can screw it into?
I use my pressure cleaner (Polaris) socket. I yank the cleaner and twist in my fountain. The water sprays quite high and a slight breeze can force it to miss the pool, I need to adjust it carefully when in use.
If you can't use that return, the only thing I can think of is a mobile standalone pump that you can put at the edge when needed.
Higher priced options include a heat pump to chill or a more economical evaporating pool chiller.