It'd probably be Full Metal Panic by Kojima Productions who've shown that they're capable of knocking grounded on-foot militaristic action + sci-fi elements out of the park. Incorporating the Arm Slaves (mechs) would be the hard part, as well as designing areas that accommodate their scale and destructive capabilities, but Kojima has experience there with Zone of the Enders. I envision it being sort of an amalgam of Zone of the Enders and Metal Gear Solid V (without the open world): get dropped into a variety of missions as Sousuke, Clousseau, Melissa, or Kurz; some call for an Arm Slave and some don't (perhaps with specific setpieces designed around the Arm Slaves like in the anime), with full control over your loadout, Arm Slave customization and upgrades, etc. like featured in MGSV and Death Stranding.