I think the nyloc nuts are NLA as well IIRC, or possibly they were just stupidly expensive compared to 10p each for stock bright plated nylocs. I use C5 A6 parts these days instead as they are close enough.
M12 fine pitch bolts tend to only be available in socket-head from hardware suppliers so OE is really the only option if you want to retain an OE look.
The grease I use for steel fasteners in contact with aluminium is an aluminium-based anti-sieze.
https://www.juicelubes.co.uk/aas-juice/
The green coating on factory hardware is also designed to be compatible with aluminium.