I'm not a fan of MC suddenly getting stuff like bio-suits or some kind (no offense to people who suggest such ideas, but they remind me too much of like Venom or Power Rangers lol).
I think my (and a friend's) idea of it would be something like the following:
Instead of MC getting a bio-suit, have him obtain a Nox-infused weapon from Fer-Tec.
This weapon is quite unique in that it can transform into smaller weapon of size; whether it's pistol, sword, dagger, axe etc.
So depending on what the user chooses, it can transform into any of the above (or other smaller weapons).
But it can't transform into something like a suit or armor due to the sheer size.
Why am I not keen on the whole suit or armor idea?
Well, it's simple.
It's gonna make MC too powerful all of a sudden (Gary Stu lol), there will no doubt be several moments like the following line:
"That Hybrid would have killed me had I not got my Nox armor on."
I've seen way too many stories where it went that route and I'm not keen on seeing that again.
Instead, I'm hoping for a weapon instead, cause I'm reminded of an example, King Arthur and the famed sword Excalibur, in the Arthurian Legends.
In the legends, Excalibur is the most powerful sword in Britain but it's not like it made Arthur unbeatable.
King Arthur was still a mortal despite the sword & dies in the end (in his final fight against Mordred) despite having it with him.
So idea is, that our MC gets this new unique Nox infused weapon from Fer-Tec.
However, despite the weapon making our MC stronger than a normal human being, compared to Hybrids' own weapons and powers, this Fer-Tec Nox-enhanced transforming weapon is only like 35~40% as powerful as actual power/capabilities of Hybrids' own weapons.
When he meets physically Another (or Sienna, I guess dependent on choice) later, she unlocks the weapon's potential (and possibly MC's potential regarding it) towards 100% so that MC can stand toe-to-toe with hybrids (not outright slaughter them, but give them a good run for their money in terms of fighting).
But until then, with the 35~40% capability, MC is still much weaker than Nox or Hybrids (and still in danger of being very much killed, maintaining the tension).
Yet at least he won't be hopelessly outmatched as like it would literally almost be a suicide without it.
As for why the weapon can't transform into something bigger (humungous weapon or bio-suit/armor) as well as why it only has default 35~40% capability, you could use lore reasoning to explain it (whether its Fer-Tec's own technological limitations or other narrative plot device).
But yeah.
That's me and my friend's two cents about it for you to consider (sorry for the long rant

) ; building up a capable MC, without getting him become too OP.