While redump.org itself does not have the Wii game database public, the Github Repository for CleanRip does have the .dat file available on the Releases tab.
Yes, but that is a normal dat file, not one with the extra data Dolphin needs. You can try it yourself – download it, and place it as a zip file at Documents/Dolphin Emulator/Cache/Redump/wii.zip. If you then verify a Wii game, Dolphin will complain about the missing data.