Yeah, I feel you. I was thinking of going with something minimal, even potentially gone, for the harder difficulty, meanwhile keeping some stats small on the outside edge for the easier.
It's in the design for the two to contrast against each other, to show that there really is a difference even in immersion. Beyond the HUD, even, I figured that when it comes to regaining health, the easier should have a general "you take meds and they patch you up, regenerating your health pool" vibe like Battlefield versus the hard's "you have to remove the bullet if it's lodged, then stitch the wound back up, and health is measured in physical and mental performance rather than a set pool" type of deal similar to Tarkov, but probably a bit more advanced (especially because Tarkov's still got health pools).
As for ammo count, I don't like being able to pull from a pool of bullets that magically fill a magazine that isn't there, so having mag count displayed on the easier difficulty's what I was thinking. As for both the easier and harder, though, you can always just look down/inspect your equipment to see how many mags or nades are left.
Any thoughts on that?