Bandai is pretty good with metalic looking plastic, a casual look at super sentai and power rangers toys really show off the famous bandai silver.

When it comes to excess mechanical detail I sincerely think giant robots look better without it. Mazinger Z's redesign in infinity was a really egregious example of ruining a good design with excess detail. To me a good robot design has a strong silhouette and tiny details distract from that.

It's not a Gundam but I know at least one Tomino robot that's a boy.

I'd love a GQuuuuuuX Guntank. It's such a toyetic design it demands a physical representation.

You're 100% right, fittingly enough this began with Tetsujin 28 and Mazinger.

There's a lot of overlap between the Galactic Avenger Battalion and the Getter Legion. Both are xenophobic empires that wear the iconography of the more heroic past. Both weild powers that seem unique to / favour humanity with Getter energy / the destiny force. Both emerge from a destroyed humanity.