I see there is a mod and save file at Mod DB by the creator "King_Kolossos" (I can't link directly to it for some reason) that could be used to get the removed content. It's the only one I'm aware of that can do so. Problems with that are as follows:
1. It's intended for an "unauthorized" version of the game. I'm unsure if that's because of before when the game used to require a constant internet connection to play, or if Ubisoft Connect still currently prevents the game using the mod correctly.
2. Using this makes Ubisoft Connect show a window after the game closes that doesn't do anything and needs to be closed. I assume it's trying to upload a cloud save and can't, but I'm unsure.
3. This comes with a game save, I figure there should be an option that's only the content unlock if possible so people can just use that without needing to start a new save game.
4. Assuming the previous 3 points can be addressed, I figure it's best PCGamingWiki mirrors this just to have a backup option.