It's an interesting idea, and would need to check if its possible and how would it work mechanically.
One thing thought is that you would need Metal to scan the biodata of soemone that can use chaos control to make that happen, or maybe plug the chaos Emerald on him to allow that?
While it has Chaos on it's names, it's most because it sounds cool than because Metal can use chaos energy. He is still ways from being able to do that.
Chaos drives could work, he would need to gather allot of them though.
And it would be a way for metal to surpass sonic AND shadow the hedgehogs. Because neither can do this.
And a chaos emerald would probably let metal do this constantly, besides having to go either raid gun for chaos drives (my favorite thing to get in sonic adventures game to level up chao abilities and such), or create a chaos drive factory.
But the idea is sound, and u even have a omakes idea for metal to learn how to do this with sage while he's on one of his empire work camp raids.
As for chaos healing, basically it would take that rounds turn for him to do so…still roll for combat but it wont be for doing damage to the enemy but for healing Allie's, both organic and mechanical. Which in this case I think he could theoretically roll a 1d4+1 for healing damaged Allie's or himself, extra healing can go to next damaged unit and so on until there is no more to heal…and that energy is wasted.
Edited: looked up some info on chaos drives, apparently made by Gerald to infuse chaos energy into living tissue, aka creating bio lizard and Shadow…which means it can be used for healing.
Heck might have allowed Maria to last as long as she did in cannon.
Anyway according to the game balance (and I agree) you can carry 10 chaos drives, so being clear here Metal could use the chaos drives as a replacement for a chaos emerald (but only has 10 charges to use his abilities I listed, some actions can be chosen to direct the charges to do more damage or healing for ultimate abilities…)
Also chao use them regularly (based on the four colors from the game's and lore), to improve themselves.
So basically with black arm cells, chaos drives, and Ragnite? The cure is in sight for NIDS people! Also the two other then black arms dna can be immensely useful for healing sick, harmed, or dying people.
Which is great propaganda for our TV series for Metal!
(Also anime as heck…sod it were making the TV show a Anime!!!)