We have been 3D scanning our koi ponds and pondless waterfalls as we build them. We finally managed to get some shape key animations working in AR, thanks @nebulousflynn for pointing me in the right direction.
I managed to get wave shape keys, on both the falls and water. I have the fluid sim, but the only way I could think to get it to work on Sketchfab was using 1 frame of the fluid sim mesh and apply a wave effect to it to get the stream to animate. I would love to hear a better way to animate the waterfalls.