Larian Studios Forums Divinity: Original Sin 2 - The Modding Dungeon Divinity - Original Sin 2 - Modding General D:OS2 on GOG and Steam Workshop content.

Just confirming what MH said, yes it works. I've done it many times.

When I published mods to both, what I do is first make the steam workshop version and "PAK" it on the upload screen. What that does is save a .pak file in your My Docs folder and uploads it to Steam. I just take the .pak file it generated from the folder and ZIP it myself manually and upload it to nexus. It's 100% the same file.