Hi, @tkn (thom),
You're quite welcome 
Actually, the source for that undocumented option came from running the sudo apt upgrade command itself that, at least back in the November 2022, returned the following "text banner":
# News about significant security updates, features and services will
# appear here to raise awareness and perhaps tease /r/Linux
# Use 'pro config set apt_news=false' to hide this and future APT news
You may find some additional context about that text banner / advertisement ("ad") in another reply of mine in that "Announcements in MATE terminal" topic, specifically the following reply:
I see that there's also the following related Q&A in "Ask Ubuntu":
Other than that, I've played a bit just now with "pro --help" commands and I've found the following command that shows all (?) the configuration options:
$ pro config set --help
usage: pro set <key>=<value> [flags]
Set and apply Ubuntu Pro configuration settings
positional arguments:
key_value_pair key=value pair to configure for Ubuntu Pro services. Key must be one of: http_proxy, https_proxy,
apt_http_proxy, apt_https_proxy, ua_apt_http_proxy, ua_apt_https_proxy, global_apt_http_proxy,
global_apt_https_proxy, update_messaging_timer, metering_timer, apt_news, apt_news_url
Flags:
-h, --help show this help message and exit
The following "Ubuntu Discourse" (also known as "Ubuntu Community Hub" or "Ubuntu Community Discourse") topic about "Ubuntu Pro", started in October 2022, is also relevant:
I think the initial message of that "Ubuntu Discourse" topic ended up as being the Official "Ubuntu Pro tutorial":
https://ubuntu.com/pro/tutorial
I've also found the official "Ubuntu Pro Client documentation", that you may want to browse:
I hope this helps