The best solution I've seen is prevention.

What you can do in P4 is work in trunk, make sure you have latest and lock binary files you're working on. If you do that you won't have conflicts (at the file level anyway). Unlike git's design, this collaborative model is centralized and synchronous but it works.

Git is missing the built in binary support, the locking, and the efficient information sharing of file status tracking. With LFS you can cobble something together but it's not fast or easy.

I'm all for other solutions but I wish git would at least support this flow more whole heartedly until something else is invented.

I guess a good way to preview things would go a long way. Merging might be unrealistic to generalize, but being able to diff on images, game engine prefabs, audio, etc would help deciding which one to use.