The package is in great shape. The only challenge to getting the package in
the archive seems to be the copyright file. Coreboot's README says
Some files are licensed under the "GPL (version 2, or any later version)",
and some files are licensed under the "GPL, version 2". For some parts,
which were derived from other projects, other (GPL-compatible) licenses may
apply. Please check the individual source files for details.
debian/copyright says most files are GPL 2+, but it my digging indicates the
majority are GPL 2 only, and I think I saw additional licenses too.
I believe upstream has recently expressed desire to make listings files with
respective licenses and/or using SPDX identifiers, rather than their lengthy
headers in the source. If that's true, checking out the Git version might help
you parse the licenses.
Speaking of which, you repacked Coreboot with the contents of 3rdparty/
removed. As a Libreboot user I thought I understood why, but as best as I can
tell those files are free. On Coreboot's downloads page they appear to
distribute the blobs separately which is news to me.