fastLED leaves the storage showing, so you can do these kinds of tricks.
And I say again that the LEDs with data and clock line can be used with no storage at all. A look at many programs shows computation to fill the buffer, then “show”. If the calculations aren’t huge, you can cut out the middle man.
You can also use a buffer larger than the number of pixels and show a subset of only the real number of pixels. This is good for some kinds of motion.