Ubuntu remote Smart Proxy to Foreman/Katello (on CentOS)

Problem:

Ubuntu doesn’t support Katello, so some commands or installer options aren’t available. Hence I’m struggling with some of the instructions provided. Some examples:

Installing a Smart Proxy Server 3.7 on Debian/Ubuntu :

Question:
This suggests enabling puppet but a Foreman/Katello deployment doesn’t have Puppet enabled, so surely --puppet-server-foreman-url serves no purpose?

Also I’m finding that (I use custom SSL certs issued by FreeIPA), I can’t use the --certs-tar-file "/root/$(hostname)-certs.tar" option for foreman-installer as the Debian/Ubuntu version doesn’t seem to support this option.

Expected outcome:

I’m either too cautious or too ignorant, but probably both. I have yet to figure out how to successfully

It took me a while to work out that v2 of the API used by Foreman Smart Proxy communication uses client certificate authentication. This is why the tar file needs to be generated on the Foreman server. At first sight, I thought the key files transferred belonged to the Foreman server, which makes no sense from a security point of view. Now I know better, but the documentation did not help in this regard.

Foreman and Proxy versions:

v3.7.0
Katello v4.9.x

Foreman and Proxy plugin versions:

n/a

Distribution and version:

Foreman server: CentOS Stream 8
Smart Proxy: Ubuntu 20.04

Other relevant data:

n/a

I am also having similar issues figuring this out. It seems like those of us dealing with Ubuntu are out of luck getting much help.