Nice list.
Most of this seems like it should be doable in 5e.
Sundering a weapon is something that should be able to happen if the target is already "bloodied", and getting sloppy.
Being at zero hit points without being unconscious or dying seems doable too: helpless without hemorrhaging.
Damage along with a push is doable.
Blocking to prevent an attack is like the dodge action or parry maneuver.
Attacked when entering melee, seems like a readied action to use a reaction.
A chokehold is damage during grappling.
In any case, I feel D&D should − with reasonably simple and intuitive mechanics − be able to represent the above combat narrative.
Agreed. Damaging while disarming or shoving is incredibly doable with existing mechanics, just needs to be allowed.
More granular grapple targets and add-on effects is simple enough. Just choose what limb or body part you're grappling during normal grapple checks. While the grapple persists, that limb or body part is not usable. Easy, intuitive, and makes grappling quite effective. If you choose the neck, if the target is not immune to suffocation, see page 183, but replace "minutes" with "rounds".
Damaging to escape a grapple really should already be a thing imho - while grappling something, after taking damage, make a Con or Str check (your choice) to maintain your grapple, same rules as Wizards and Concentration checks. Gives folks meaningful outs to the above.
Attacks while entering melee, Polearm Master just needs to not be needlessly tied to one weapon type.
Being Incapacitated rather than Unconscious when knocked to 0 until / unless specifically knocked out afterwards imho should be the default behavior.
Using the environment to gain advantage and / or deal additional damage, and specifically disabling body parts, is a bit tougher, but that's more than 70% of the list with just a few sentences of added rules. I definitely feel that, for the most part, D&D absolutely could support more complex and varied options for martial characters without significant additional lift, maintenance, or rules. I'll check out LevelUp and see what I can see, but stuff like the above is such low hanging fruit that for now I just houserule it, doesn't change the fact I'd love to see it baked into the core game. Anyway don't mean to tangent too much, plenty of threads to discuss this kind of stuff, was just trying to provide specific examples to the inquiry posed.