FYI, this package is already built in EL9 [0], it just isn't shipped.  There is an existing request to ship that package in CRB [1], but no action has been taken yet.  It could be added to EPEL9 in the meantime, but if/when it's added to RHEL9 it will need to be removed from EPEL9.

[0] https://kojihub.stream.centos.org/koji/packageinfo?packageID=2566
[1] bug 2037812

Unfortunately, we are not generally aware of internal requests.
Additionally, I am not sure whether the package would work correctly, considering RHBZ#2100618 and https://gitlab.com/redhat/centos-stream/rpms/go-rpm-macros/-/merge_requests

Bug 2037812 is not an internal request, it's a public bug that anyone can view.  It's fine that this bug was opened, I just wanted to make the maintainer aware of the other request as well.  If you want to check for open bugs like that before filing an EPEL request, you can do an advanced search in bugzilla with only the component set to view bugs across RHEL, Fedora, and EPEL.

https://bugzilla.redhat.com/buglist.cgi?bug_status=__open__&component=golang-github-cpuguy83-md2man

I don't think golang-github-cpuguy83-md2man will be affected by bug 2100618 because it doesn't use %go_generate_buildrequires.  After all, it built fine for CentOS Stream itself.

Will you be able to branch and build golang-github-cpuguy83-md2man in epel9?
The EPEL Packagers SIG would be happy to be a co-maintainer
if you do not wish to build it on epel9.

I'm also interested in seeing this package land in EPEL9, be that via CS9 or via EPEL9 directly :)

I am still confused with bug 2037812: whether we need to provide "golang-github-cpuguy83-md2man" to EPEL9, given it's provided to CRB and (supposedly) CentOS Stream 9.
Don't know about CRB release details though, and haven't got an answer in the ticket above.

As for now, I see "golang-github-cpuguy83-md2man" package available in CRB both in RHEL9 and AlmaLinux9.
I believe we can close this ticket. Otherwise, please reopen with more details.

----------------------
# dnf info golang-github-cpuguy83-md2man
Updating Subscription Management repositories.
Last metadata expiration check: 1:11:30 ago on Sun 14 May 2023 12:07:35 PM BST.
Available Packages
Name         : golang-github-cpuguy83-md2man
Version      : 2.0.2
Release      : 4.el9
Architecture : x86_64
Size         : 773 k
Source       : golang-github-cpuguy83-md2man-2.0.2-4.el9.src.rpm
Repository   : codeready-builder-for-rhel-9-x86_64-rpms
Summary      : Converts markdown into roff (man pages)
URL          : https://github.com/cpuguy83/go-md2man
License      : MIT
Description  : Converts markdown into roff (man pages).

# cat /etc/redhat-release 
Red Hat Enterprise Linux release 9.2 (Plow)
----------------------
# dnf info golang-github-cpuguy83-md2man
Last metadata expiration check: 0:02:00 ago on Sun May 14 13:34:03 2023.
Available Packages
Name         : golang-github-cpuguy83-md2man
Version      : 2.0.2
Release      : 4.el9
Architecture : x86_64
Size         : 770 k
Source       : golang-github-cpuguy83-md2man-2.0.2-4.el9.src.rpm
Repository   : crb
Summary      : Converts markdown into roff (man pages)
URL          : https://github.com/cpuguy83/go-md2man
License      : MIT
Description  : Converts markdown into roff (man pages).

# cat /etc/redhat-release
AlmaLinux release 9.2 (Turquoise Kodkod)
----------------------

I've filed https://issues.redhat.com/browse/RHEL-4448 as the -devel package is still missing, which blocks the dependent ticket.