I don't know if you ever read my writeup that the Fatima in Five Star could cause the mecha's powerplant to run over the design specs even up to a V-Max style event. Basic Fatima and Etriml (brain in jar) could not perform like a high end designer Fatima could.

My personal rule of thumb was that near future mechs would never get past 4x because we had motors that could be 100x stronger than a human and a 4x tall humanoid mech would weigh 64x what a human does without armor and weapons. This completely ignores the power source mechs always ignore.

Yeah, there need to be a lot more critters for this setting, the Wyvern are not the largest predator. The flying whale Sarah did is one of the bigger filter feeding critters in the setting.

Is it tall enough to roll a wheelchair up to it?

Yeah, we went either the roll from the first movie. Soon we might do this one too.