i saw a report that netbsd-8 can't be built on -current but i'm not finding it right now.
i can confirm this is the case. you can work around the GCC 10 inspired issues for now with eg: ./build.sh -V HOST_CFLAGS='-fcommon -O2' but then there is a -current regex vs -8 file magic regex issue. christos and i working on fixes for that. .mrg.