Hello, I have put in https://github.com/nmav/nettle-mini/tree/gmp-mini a version of nettle that has an additional configure option. The --enable-mini-gmp. This will compile libghoweed using mini-gmp thus allowing nettle to be used in space constrained systems. Note that using nettle with mini-gmp instead of gmp imposes a penalty of around 10x, and may leak more information due to side-channels (this should not be the case for RSA as blinding is performed in hogweed, but I haven't checked the other algorithms).
regards, Nikos