The s1012 pro takes the same tips as the TS100 and the Pine64 Pinecil. I recommend the TS-D24 or TS-C4.
It also fits Hakko T12 tips (the longer ones), and a T12-D4 is another good one.
Either the TS or Hakko tips are available on Amazon and many other places.
Having a nice beefy chisel or wedge tip will help a lot with soldering fat wire on nickel.
