Kids will play in a pool with almost nothing if the water is clean and the grown-ups are nearby. You do not need a supermarket trolley of plastic.
Sinkable rings, a floating hoop, coloured ice blocks in a tub at the edge, and a simple treasure hunt with weighted toys are enough for an afternoon. Keep anything electrical away from the water. Skip glass. Watch small parts. Pool toys should be easy to get out at the end of the day so they are not sitting on the floor of the pool overnight.
The best toy is still a pool that was built for the family who uses it. Steps they can manage, a fence that works, and water that is actually warm enough in the afternoon. If you are planning a family pool, we will design the shell around how your kids swim, not around a catalogue of accessories.