This idea would be for immersion sake only, and i know some might thing this is a silly idea. But this is a game with a lot of random flavor that makes replaying special compared to some other games.
I love how in the details of combat you can see who killed who, and the type of unit that was the killer, you can imagine what happened, eg. an Artillery unit getting killed by some Bikers who had broken through.
What would be interesting is having a list of WAR CASUALTIES random info and end of text report; first and last name, age etc. And these names could go onto a Global War Casualties list over the course of the game where you could click on that and for immersion view them them all. Xcom2 has this, although its more on a personal level as often you get to rename them and choose how you level them up etc, often some of them you rely on their higher skill level until they get killed and their death means more. In this game of course units are just numbers and variables in a large Army.
Perhaps this unit personnel info could add/created on the fly when creating a new formation (and also the automated Miltia replacements/recruits) a list of names and basic details are randomized, which could be a tab to click on to view this when selecting a Battalion, those who do not care for this at all won't even see it.
Taking it a little bit further, perhaps even listing 1 main hobby. This could also add to world building immersion too- lets say one of the possible hobbies listed is 'golfing' and say your current gameworld is mostly desert- so you could imagine a desert golf course that perhaps has some vibration tech to harden the sand so the ball won't sink- i mean the player can come up with stuff too). If 'Surfing' was listed- and there is no ocean anywhere, then one could assume it's VR Surfing or is just an interest; like the soldier reads about it and watches videos of it from the past.
The hobby listed could just give the soldier a little personal touch. Those who want to roleplay a little or are doing some creative AAR could use some of this information to personalize it a little (of course even without this idea- they still could) but the point is even in the real world when applying for a job, the application form sometimes lists interests for you to fill out which has nothing to do with the position, but is still something for an employer to get a tiny picture of what interests you.
You can sort of picture what kind of person they are from just 1 interest example bookworm vs outdoor hunter.
So I am not suggesting a great list of personal interests and likes and dislikes, or anything like that. But just some basics as per suggested already. Perhaps some modder can add more information later on if players want that especially AAR roleplay where you might do a Journalist/Writer tags along with a Battalion for a few months kind of thing. And a mod adds more interests and personality quirks, basic education level etc.
I think aside from the initial compiling a list of first and last names; ages and single hobby/interest would be the easiest (mirror the real world- with some sci-fi flavor too) it would be quite easy to implement and add into the game.