I tried entering a 64 character hash in Blue Wallet yesterday and it worked. It's obviously not air gapped, but I don't plan on using the wallet anyway. A hash of a large file nobody has ever seen shouldl produce 256 bits of entropy. This obviously does not apply if the file you hash is Romeo and Juliette.

Pictures of yourself naked in front of the mirror are more secure, assuming you don't make a habit of making naked pictures public. 😂