At least 1.3 billion people live in poverty, much more than 10%.

That depends on your definition of poverty; 10% of the world is in “extreme poverty” of $1.00/day in 1996 prices ($2.29 in 2021),

But this device has the exact same problem you're describing, is less efficient, costs more and requires power. Novelty is the only upside

The only device I could find on Amazon that fits the description of an inflatable desalination device is https://www.amazon.com/Aquamate-Solar-Emergency-Purification... and it reportedly produces between 0.5 and 2 liters of water per day. That’s great if you have none, but the device being discussed here produces substantially more. So it’s not just a novelty thing.

Efficiency is less important in scenarios like tropical storms, drought, and infrastructure crises, or places where common western infrastructure is non-existent. Costs are also less important as they are cheaper over time as the costs of maintenance becomes lower. Places lacking infrastructure are also helped by outside organizations who donate knowledge and equipment. Considering that this device can be solar-powered (and these bespoke areas where infrastructure is non-existing generally are _very_ sunny), requiring power seems like a lesser problem.