You can route DDR in KiCad and there are some online reports of people doing that. KiCad is not as nice as the paid software and there are shortcomings but I think 'pretty useable' covers its status accurately.

You "can" make fire with a piece of string and some sticks in a pinch.

I wouldn't describe this as a "pretty usable" means, however, for the same reasons KiCad is unusable for DDR routing.

I think that's hyperbolic. There are several designs advertised as being designed in KiCAD that have DDR which means there are way more not being advertised.

https://www.kicad.org/made-with-kicad/categories/Single-boar...