I didn't look much into void, but when I did, gentoo's repository is much larger and there are many packages that I'd call obscure that happen to be in the main repos.
The situations I've had to reach to guru are rare. I bet that gentoo has more obscure stuff in its main repo, though I don't have the numbers to prove it.
A symlink works more closely to the first way you described it. The software opening a symlink has to actually follow it. It's possible for a software to not follow the symlink (either intentionally or not).
So your sync software has to actually be able to follow symlinks. I'm not familiar with how gdrive and similar solutions work, but I know this is possible with something like rsync