Love this game for what it does right (the city and outskirts, the setting, the design and the colorfull characters) It's a great but buggy first person action RPG but definitely NOT an immersive sim. It's closer to Witcher 3 meets GTA in 80's retrofuture style than Deux Ex bring's Akira to dinner,
If it was an immersive sim, you would be able to kill important NPC's and still be able to finish the game.
If it was an immersive sim, you would be able to acquire any plot items any-time by going to the right place independently of a quest marker asking you to pick it up.
If it was an immersive sim, your actions would have reactions, sometimes permanent, in the world (ex: fluid gang territories, bounty on your head, new gig's where there was none before or related to previous consequences, NPC's or locations turning hostile to you or refusing to talk to you (there is one such case here), etc...)
If it was an immersive sim, NPC's would react to you picking up their stuff in front of their eyes or dropping crap on the floor like mines (why can't we pick up and arm mines anyway ?).
If it was an immersive sim, you would be able to complete the game by heading to the right places at the right time in some obscure way and completing the main objectives instead of having quests locked in their own bubble and not interacting one with another). It could be by using some very specific dialogue choices (could be locked behind skill checks), using or finding specific plot items . Includes ending the game without hurting a single soul or on the contrary killing everyone on sight.
etc... Just go and play some of the games that fall in that genre to get a gist of it but more notably the first Deus Ex.
For Cyberpunk 2077, this would require a lot of fundamental changes but mainly around the way the missions work (the yellow ones) by making, for example but not limited to, the main objective the only requirement to complete it and having side objectives not mentioned at all unless V was told about them (no game designer hand holding with map markers). Every NPC must be killable resulting in more work on the scripting. But every NPC must also react to you trying to kill them (it should be hard to get away with it though).
Examples :
If Judy dies when she's following you or waiting for you in the van for some reason, then that's a bummer but shouldn't prevent you from still being able to find clues in that general Evelyn quest-line. You can also try to shoot her resulting in the Moxes turning on you on sight while degrading your general notoriety and potentially locking you out of some missions.
How about skipping parts or entire missions by raiding places before you were tasked to do so and as such acquiring quest items out of order before you need them while still getting clues by fixers about such items and thus unlocking future missions or gigs ahead of time.
How about finding where that boxer, Razor lives or hangs out and poisoning him before the fight, or killing / blackmailing / making him NCPD wanted or a gang target, or enhancing yourself in a weird way or using a combination of items that makes the fight trivial, almost glitch like (I beat him the intended way on the n'th try but that was a pain. Almost felt like you're intended to loose) ...
Anyway, as you can see, there is a LOT of work to make this possible so no chance of seeing this unless CD Project changes the way they do Game Design for Cyberpunk 2. No more map with EVERYTHING on it, no more perma locked doors or single point entry missions/locations, no more invisible or untouchable items until a quests says otherwise... etc...