pg_config header files are missing - Postgres 13 - Amazon Linux 2

Hello!

We've a web application in play framework which uses Postgres 9.6 with plv8
and uuid-ossp extension. We now want to use Postgres 13 instead of 9.6. To
achieve this, I'm trying to install Postgres 13 (on the same host where 9.6
is installed) with plv8 and uuid-ossp extension.

PLV8 <https://plv8.github.io/> "make" uses "pg_config" to get the latest
version of Postgres (in case multiple Postgres are installed). However,
when running "make" with Postgres 13's pg_config, its giving error:

cat: /usr/pgsql-13/include/server/pg_config*.h: No such file or directory

using command: make PG_CONFIG=/usr/pgsql-13/bin/pg_config

I see the header files are missing, in fact there is no "include" folder
inside "/usr/pgsql-13/"
--
# ll /usr/pgsql-13
total 16
drwxr-xr-x 2 root root 4096 Dec 29 02:31 bin
drwxr-xr-x 3 root root 23 Dec 29 02:31 doc
drwxr-xr-x 3 root root 4096 Dec 29 02:31 lib
drwxr-xr-x 8 root root 4096 Dec 29 02:31 share
---

Header files (and include folder) do exist in Postgres 9.6's pg_config.

After a bit of research I found that probably installing
"postgresql13-devel.x86_64" will install pg_config with headers. However,
when installing "postgresql13-devel.x86_64" via yum, it says,
--
Error: Package: postgresql13-devel-13.5-1PGDG.rhel7.x86_64 (pgdg13)
Requires: llvm-toolset-7-clang >= 4.0.1
--
I didn't find "llvm-toolset-7-clang" from yum repo, except from the RHEL
subscription manager, which is paid for non-dev stuff. So I tried to build
llvm-toolset-clang from scratch, but that doesn't solve the problem.

I'm not sure why the header files of Postgres 13's pg_config are missing?
It appears pg_config got installed as part of Postgres 13 itself. I'm also
not sure if copying 9.6 pg_config header files to 13 is the correct way?

What would be the next steps here? Please advise.

Some info about host machine: This is Amazon Linux 2
---
# cat /proc/version
Linux version 4.14.256-197.484.amzn2.x86_64 (mockbuild(at)ip-10-0-37-156) (gcc
version 7.3.1 20180712 (Red Hat 7.3.1-13) (GCC)) #1 SMP Tue Nov 30 00:17:50
UTC 2021
---
--
yum list installed | grep -i postgre
postgresql13.x86_64 13.5-1PGDG.rhel7 @pgdg13
postgresql13-contrib.x86_64 13.5-1PGDG.rhel7 @pgdg13
postgresql13-libs.x86_64 13.5-1PGDG.rhel7 @pgdg13
postgresql13-server.x86_64 13.5-1PGDG.rhel7 @pgdg13
postgresql96.x86_64 9.6.24-1PGDG.rhel6 @pgdg96
postgresql96-contrib.x86_64 9.6.24-1PGDG.rhel6 @pgdg96
postgresql96-devel.x86_64 9.6.24-1PGDG.rhel6 @pgdg96
postgresql96-libs.x86_64 9.6.24-1PGDG.rhel6 @pgdg96
postgresql96-server.x86_64 9.6.24-1PGDG.rhel6 @pgdg96
---

Thanks!
Naqvi