I feel like one of the biggest design victories of XCOM 2 is that when you play on Commander all of your characters start with 4hp, which is JUUUUUUST low enough that the basic grunt the game mostly throws at you at the start will take any of your guys down to 1hp on a normal hit and instakill on a crit. This immediately feels incredible and terrifying. And then early game you have a equipment item you can research and craft that gives a soldier you equip it on exactly +1 HP. On other lower difficulties this is a nice bonus but on Commander it is JUST enough to bring that character's HP out of the mook one-shot range and the feeling of becoming immensely more survivable is like opening the window and having the sun blast your eyes. It's a minor upgrade that makes literally all the difference in the world.
That feeling of even the tiniest incremental upgrade being a HUGE deal because all the numbers are so small is glorious. It's one of the things i really deeply love about early game XCOM2. And it really, uh, characterizes who you choose to give your initially limited stock of armor upgrades to. Who gets to probably live? Who is a sad baby who is probably going to get shot in the face? It's things like this that lend SO much character to the moment to moment