You will spend a bit more buying a few of them, a 12v power adapter, and the shell to tie everything together, but you are correct.

If you buy the cylindrical air filters, you can pop one on a table, pop a case fan on top, and hook it up to a phone charger via a 20 cent Usbc adaptor.

As a bonus, the USB-C PD adaptor has selectable voltage (5, 9, 12v) on little dip switches, and that can be used as a speed control for a 12v fan.

Turn it up to max when cooking, and down to silent again when sleeping.

No need for any fixings or case or anything.