Are the expansions being sold somewhere online? I'm a believer in abandonware/piracy sites as a means to keep games alive until they're sold legally again.

I'm willing to provide an ISO copy of this disc (I assume you'd need the base game to play), but at the same time if the expansions can be bought online at a reasonable price I don't want to help illegitimate piracy.

Anybody's thoughts? Maybe the expansions can already be easily found online?

Both expansions are available on Steam for 4,99€ apiece.

It says on Steam you have to have a Steam copy of Ghost Recon to play those. Is there any way around this?

I can just copy the expansion files from my Steam games to my GOG copy and it works fine. You need to own all 3 Ghost Recon titles (Main game and two expansions) though.

Copy "Tom Clancys Ghost Recon\Mods\Mp1" and "Tom Clancys Ghost Recon\Mods\Mp2" folders from a Steam copy of the games to the same path inside your GOG copy and voila.