Already exists. Whether it’s up to date or not is another question. It is maintained by the community in the Wiki.
Top of Wiki: Librem5 / Librem 5 Community Wiki · GitLab
Cellular Providers: Cellular Providers · Wiki · Librem5 / Librem 5 Community Wiki · GitLab
As with any information, there is a cost (in time at least) in maintaining it - and maintenance doesn’t always happen.
I agree completely that you should not have to go digging in a forum - because it is hard to find stuff, you can find everything including things are no longer applicable, you can find lots of irrelevant stuff.
Philosophical / business question: What is Purism’s best bang-for-buck in terms of spending time making this kind of documentation available v. improving the product (which serves to make parts of the hypothetical documentation out of date)?
Purism sells a dock that is reportedly compatible with the Librem 5. Cost: US$49
Tested Accessories: Tested Accessories · Wiki · Librem5 / Librem 5 Community Wiki · GitLab
(ironically noone seems to have thought to add that model to the Wiki - and as I don’t have one I won’t be spontaneously adding it to the Wiki)
I don’t have any personal experience using it but: New Post: Snitching on Phones That Snitch on You - #15 by Kyle_Rankin
I agree though that users have expectations that this kind of thing can be installed at the touch of a button.
Partly covered by: Tips & Tricks · Wiki · Librem5 / Librem 5 Community Wiki · GitLab (although it looks like someone has butchered the formatting)
I think creating a shortcut to launch a web page is already there as functionality.
You can boot Jumpdrive on the phone and then from the host computer dd the internal drive of the phone. dd to another phone of the disk image should have the effect of cloning all software and settings. (Of course after doing that, if you are using a static IP address for anything then you would need to change the IP address. Likewise you will probably want to change the hostname.)