The character is broken into many individual slots, as you can imagine: rims, chestpieces, shins, kneepads, etc. This is to facilitate any customisation, rank visualizations and allegiances we want to add in the future.
As for the player-facing customization, however, we haven’t finalized this yet. It shouldn’t be surprising at all (shoulders, backpack, etc), we just haven’t done the final checkoff yet.
Note that for the most part the bits and bobs outside of the armour (trophies, belt accessories, iron halos) are actually being treated as accessories that you earn through progression and have stats or other effects associated with them.