I'm in favour of adding this, it seems useful. However it kinda violates some core assumptions encoded into the pkgrepo api currently. I think it will need some reworking to handle this properly, particularly since we support invoking pmbootstrap build $subpackage and then figuring out which package the subpackage belongs to.
I know it's not nearly as good, but this inspired me to open !2472 (merged) which might help bridge the gap for now. With that it becomes
$ pmbootstrap build systemd[17:19:00] ERROR: Could not find aport for package: systemd[17:19:00] See also: <https://postmarketos.org/troubleshooting>Run 'pmbootstrap log' for details.Before you report this error, ensure that pmbootstrap is up to date.Find the latest version here: https://gitlab.postmarketos.org/postmarketOS/pmbootstrap/-/tagsYour version: 3.0.0_alphaChannel: edge (pmaports: master, dirty)Device: qemu-amd64 (x86_64, kernel: edge)UI: consolesystemd: no (not supported by pmaports branch)