Can you put the enhanced version on GOG as well?

[Palito]

I already bought Oblivion three times before.
Or you could have it here for download.

[Kermit 61]

I'm guessing you don't own the Steam version of Oblivion which is required for Steam Nehrim.

No, a conversion for GOG or a version here for download is currently not planned.
Our (few) developers are working on a completely new project of their own, so there is no time for that.

But the Steam version of Oblivion can be found from time to time as an offer on Steam or on the internet.