How bad is Kensei Monk? 5.5e

Recently been playing the latest Resident Evil, got hooked to the saga again so i started replaying the older games aswell and i just love and love Albert Wesker, so much so that i decided that i want to create a similar character for the next season of our campaign (Which is actually set in Runeterra, LoL's world) that is nearing it's end after 3,5 years.

!!I'm also gonna describe a character from the latest Resident Evil 9 Requiem so if you don't want to get spoiled ANYTHING do not read!!

So, i love what capcom did with Zeno, basically a "clone" of wesker, i love his design and his combat style which is pretty much the same as Wesker.
Using martial arts with superhuman strenght, speed and reflexes, regenerating the body and using a beautiful sexy one round pistol (and the way he dodges the bullets!! love it).

So the idea is of course playing as a monk for the reflexes, speed and close quarter martial arts combat and very high AC to basically dodge anything.
However i want the pistol to be a important factor for the combat aswell.
With a quick research i found out about the Kensei monk which let's me basically use any weapon and apply some buffs over it, however it seems to be kinda bland and underwhelming, my master also laughed at me for considering this subclass lmao!

So then i considered maybe another monk subclass with a multiclass to a fighter or something, i honestly don't have any clear idea right now.
Also multiclassing have a huge con because i'd miss basically the level 19 and 20 monk feat which is essential for high AC.

So, is Kensei actually bad? would it help with the gameplay i'm trying to achieve?
In summary the combat aspects should be:

• Super speed, reflexes
• Inhuman strength & martial arts
• Regeneration (Probably going with Dhampir)
• One bullet destructive pistol shot <-- Key aspect!

I'd actually be so gratefull if anyone would help me with this!