How to set up debian before the first network connection?

Question

Information Security

Good day, gentlemen. Can any experienced linux expert tell me what I need (or can) do in the settings / configurations of pure debian (in my case xfce) before the first connection to the network? Interested in the side of anonymity\security\confidentiality. In order to avoid repetitions, I will write what has already been done:
1. /etc/NetworkManager/NetworkManager.conf - mac-address=random values ​​​​are registered for different types of connection
2.ssh keys are configured, a key is generated for connecting to your own vps, as well as /etc /ssh/ssh_config - changed ports, root login=no, etc.
3./etc/resolv.conf - change server dns to cloudfare and opendns servers
4.as well as disable terminal history in /.bashrc
What else can be done? guides on YouTube \ form and publics on anonymity did not bring results in search of information, everything is rather meager, most manuls go to ready-made oc, like kali and parrot, and in pure debian many packages are not preinstalled and you need a network connection and I would like to protect yourself as much as possible (and, if possible, hide) before its first connection. The last hope for habr)
PS I'm not going to deal with rubbish, I'm just paranoid and this topic is interesting)

Answer 1

As a rule, you need to start with building a threat model. Those. you need to consider possible attacks on your computer.

Answer 2

Oh. The topic is interesting, but is it not interesting to build a threat model? And they always start with her, dear. Well, that is the very question that beats like a refrain in Agatha Christie's song "Two Ships" :) - "Na##ya"? What are we trying to prevent, what are we trying to protect ourselves from, who are we considering as an adversary?
Opponents have different capabilities, means and methods. To protect against some, banalities are enough, to protect against others - decent methods, and there is no way to protect against third ones - this is why the issue of building a threat model is given such importance