Those are solved issues.

> oxidation at high temperatures

SLM machines typically use an Argon gas chamber. DED machines use an Argon gas shield.

> It’s more typical to print copper alloys than pure copper.

In the context of modern SLM, it depends on your definition of "pure" and "alloy". During the process, a bit of resin to is mixed into the powder and heat treated in a final step to get to 99.9% pure copper.

edit: Just fixed up my knowledge. Indeed alloys are typically used (99% copper with things like Chrome added on depending on use-case), tough the pure copper can be used with higher laser power.