I'm indeed working on it (meta-issue progress tracking is over there: https://github.com/SerenityOS/serenity/issues/8605). However, bootstrapping pkgsrc is a stressful test of reliability, stability and POSIX-compliance for any operating system, let alone a hobbyist one. I've yet to have a pkgsrc bootstrap finish successfully without hitting a bug, deadlock, coredump, kernel panic or some combination thereof. It's like repeatedly stubbing one's toe on a sharp POSIX edge.
That's not counting actually building packages inside SerenityOS (pkgsrc doesn't support the kind of cross-compilation we'd need to build packages on a Linux host for a SerenityOS target), which will probably expose lots of other bugs, race conditions and limitations.
If anyone wants a third-party software repository for their OS project, it's worth checking out NetBSD's pkgsrc:
* https://en.wikipedia.org/wiki/Pkgsrc
It's multi-platform (Linux, BSD, macOS, Solaris, AIX, QNX, etc), and so has a lot of infrastructure for portability already set up:
* https://www.pkgsrc.org/#index4h1