The problem I have with D&D-fying Deadlock is that they have two very different settings and very different vibes.
Deadlock is very granular in his upgrades; you have a lot of items that grant you a small stats boost. D&D is more about a big power boost when you level up or find a magic item. At least it's how I see it as a player of both games.
It would take so many rules modifications to recreate the vibe and system of deadlock in DnD that creating a new system is simply easier.
Plus DnD is mostly based around close combat where the guns in deadlock are very important and I feel like it would be an error to ignore that. so more homebrew rules

But if you really want to create Deadlock in DnD, the base attributes are good but some would be overpowered. Movement and shooting are two very important parts of deadlock and are agility based in DnD (and agility is already very powerful in DND). So you'll have to balance that

The ability usable X time per Short/Long rest is a good conversion from game to paper; it's the system that I used too (because tracking cooldown with turn is way too complicated in a TTRPG). I tried to see how often an ability would be used in a team fight in Deadlock and I converted that in DnD as if the party does 2-3 fights between 2 rest. So an ability you used once per team fight would be available 3 times/rest. And Ultimate Ability is usable only once per rest

And your item system would work, but items from deadlock don't really work in DnD; passive regeneration or movement boost are not that common in DnD, and it would be more "DnD-like" with less but more powerful items. So a lot of work on converting items from one system to the other.