On aluminium, tantalum, also titanium, niobium, chromium, you can grow an oxide layer by anodization. Fast enough?
On copper and supposedly others, you can deposit a lacker. It's done for transformer wire, decades of experience is available. Very strong, excellent and known insulating properties. The heat resistance distinguishes the insulator class, going through Peek to polyimide (180°C).
Conformal coatings exist for printed circuit boards. They insulate, protect from moist, and cost a bit. Made by parylene decomposition and local lukewarm recomposition as a polymer. Fast enough?
As a gut feeling, it must take months and years to stabilize the process, so subcontracting must be better for one-time needs.
EDIT:
FYI note - lacker is a noun that is a variant spelling of lacquer