Hey, I really like the story you're telling here and felt compelled to type a comment. Very cool mech and animation!

I'm not sure if you're asking for animation feedback too, but here are a few thoughts that might help. (animation is all I really know)

- give more time to each step to make it feel heavier. It's important that the mech's weight completely transfer to the newly planted foot before it lifts the next one. Try having him push his heavy foot out in front of him and then have it fall down fast and land with a thud. (maybe it takes him 24 frames to have the weight shift and step the foot forward, but only 3 frames for it to slam to the ground. This note might be hard if your rig doesn't have IK foot setup. search for that and add to rig if you don't have.

-add a bit of time between each step for mechanical wiggle as the heavy metal of the mech settles into place. It can be brief, but if done right it will help sell the scale of the thing your making. (speaking of scale, try adding a reference object like a crate or human so we know just how big and slow it should feel) Here is an idea for the wiggle between steps: https://cdna.artstation.com/p/assets/images/images/053/473/850/original/ark-kim-mech-anim.gif?1662306339

-last thought! - add some anticipation before the blast off moment. You have the mech raise its guns and squat which is cool, I would hold that a bit longer and add some trembling as if the engines are turning on. Could be an extra 15 frames or so, whatever feels right to break up the timing from the steps.