Don't know if you are still taking suggestions or not as kinda saw this late, if you do then probably I will say would really wanna see MC get into action real quick, especially with the precious hammer he's gonna go for. The build-up till this point has been fantastic but probably I reckon if it their bunker training gets stretched too long, might slightly frustrate the rhythm of the plot. You have done impressive with the narration so far so I do know you are aware of your stuff which makes it interesting where you are gonna take this forward to, starting with chapter 22 itself as the wheels definitely had turned in chapter 21, which sure will have consequences to spice up the story, particularly in the combat part. Dunno how constructive/intelligent my suggestion was lol but yea that is the only suggestion I have, rest feels perfectly authentic with narration and theme of the plot which really makes it a high-ranked AVN in the thriller genre in my opinion at least.
Thanks for reading Dev, best wishes for ahead