To be clear, you can certainly qualify for eurobonus gold without ever flying SAS. Points on LH for example (while miserly) are basic points and thus get you towards your goal.
You become a Gold member with
45 000 Basic points* with SAS,
Estonian Air, Wideroe, Atlantic Airways and Star Alliance carriers.
If you on the other hand want to get there by qualifying legs, These need to be on SAS or Wideroe
see here:
https://www.flysas.com/en/eurobonus/...p-levels/gold/