Pool heating method

Hello r/swimmingpools I recently moved into a home with a fairly large inground pool, we do not have a solar cover or heater for this and live in the midwest where, while it can get very warm, the pool is already only usable a few months of the year. There is some tree coverage that shadows the pool for part of the day, we are hoping to get branches trimmed to fix this but aside from that -

We are looking into methods of heating the pool while being cost efficient (liquid cover, solar cover, even some home made 'pintrest' type heating mats, etc) and were hoping for some input before investing in something that is ineffective.

Some home made things we have seen are things such as black plastic around hoola-hoops and I came accross "thermaspring solar mats" on a website.

I do not have exact dimensions now but will come back with an edit and more detail. I would estimate about 20 x 60 with a shallow end of 3ft and a deep end of 8ft.

Any suggestions or thoughts are greatly appreciated!