IPv6 has been around for years.  Why don't some people get with the
program, instead of coming up with hacks to get around the address
shortage.  Even with this block, there still won't be enough IPv4
addresses just for mobile devices, let alone everything else.  The
longer people take to move to IPv6, the worse the problem is going to
get.  By comparison, on IPv6, the smallest address block, /64 provides
as many addresses as the entire IPv4 address space squared.  I get 256
of those /64s from my ISP.  Some ISPs provide 65K of them to each
customer.  Why are we wasting our time trying to squeeze more life out
of something that should have been retired years ago?  Incidentally,
this block represents less than 0.4% of the IPv4 address space.  Will it
really make a difference?

https://www.technotification.com/2019/08/linux-kernel-allows-0-0-0-0-8-as-a-valid-address-range.html