Using sandbox to test pkgsrc port/package within sandbox
Now go into that dir and setup sandbox as follows
$sudo ./sandbox mount
now you will see
# at prompt means you have entered sandbox now fetch pkgsrc -stable branch into sandbox
#cd /usr && cvs -q -z2 -d anoncvs@anoncvs.NetBSD.org:/cvsroot checkout -r pkgsrc-2020Q2 -P pkgsrc
for getting various other branches and updating click here
After this you should be able to see pkgsrc under your sandbox now fetch WIP pkgsrc branch for that you will need to make git under sandbox:
#cd /usr/pkgsrc/devel/git && sudo make install
#cd /usr/pkgsrc/ && git clone git://wip.pkgsrc.org/pkgsrc-wip.git wip
now you can port or import new applications under sandbox.
If you want to build your own repo under sandbox using pbulk click here for more info.