[anArbitraryOne]

Not quite. This is kind of complimentary to the anamorfake techniques in that it squeezes the image, which the lens mods don't do, but doesn't produce oval bokeh.

I got one on Ali Express for ~30 USD and I think it's pretty much the same as the more expensive ones elsewhere.

[actionfromafar]

If the bokeh was circular before, how can it not be oval after you flatten the image?

[anArbitraryOne]

Good point, I should have said vertical oval bokeh. Desqueezing will produce slightly horizontal oval bokeh, but the tiny bokeh balls that smartphones are capable of being ~25% wider (not 33% as advertised) is going to make fuckall difference. For example https://www.youtube.com/watch?v=MV-GGmTiyyc