> their approach still spends 7 bits on the prefix.

The Yggdrasil people are very clear that this is a research project. Not to be used in production, to be used at your own risk etc etc etc.

In that light I find it unfair to claim it spends addressspace. Which, I might add, is pretty darn huge and we are not going to run out of addresses any time soon. If ever.

Maybe pedantic, but needed to point out that the 7 in `0200/7` of the usage is the opposite of being spent. The 7 first bits are the mask you need to apply to indicate that it is INSIDE the yggdrasil address-space. Which means that they only 'spend' 1 bit from from the first byte. Not 7.