Well, it seems that XDA Developer "ProtoDeVNan0" was able to pull that Android 8.0 Oreo firmware of S7 edge based on Samsung Experience 9.0 and convert into a working Custom ROM.
Developer notes that the Samsung Experience 9.0 ROM works only for the Samsung Galaxy S7 edge with model G935F. In order to install this ROM, you'll need an unlocked Samsung Galaxy S7 edge with TWRP Custom Recovery installed.
You can download the Samsung Experience 9.0 ROM zip file from below and install it via TWRP after wiping the Cache, Data, System, and Art memory.
There's no information when Samsung is going to push the public rollout of Android 8.0 Oreo for the Galaxy S7 and S7 Edge. Samsung has already started Official 8.0 Oreo rollout for the Galaxy S8 and S8 Plus, so expect the S7 family to get update after a few months.
Download: S7 Edge Android Oreo ROM //XDA