Instead of using a QR-code to share a dat://-URL, you could also share a dat://-URL if all possible dat://-URLs would be put into a table [multi-dimensional]. Then this table could be shared openly with the person whom you want to share the dat://-URL with. Then both you and the other person look up the dat://-URL in that multi-dimensional table by using an App into which both you and the recipient enter the same words in the same order.
Then because both you and the recipient have access to the same dat://-URL, you could then use that dat://-URL to have sort of like a secret chat-channel, over which you can communicate or also share other information, such as a website. The key for this to work is that you are able to share the words which are needed to look up the dat://-URL in the table secretly with the recipient. This could e.g. be done by writing the words on paper and then secretly handing the paper over to the other person.
(This seems to align with the information I came across maybe some years ago, wherein was stated that people who write on paper are considered “domestic terrorists”. However, I dom’t know whether that list/classification was by the FBI or the CIA or the US government or some other institution.)
Assuming the dat://-URL has 16^64 possible combinations (because it has 64 digits whereof all can contain the digits 0 to f) then a multi-dimensional lookup table would be needed which can contain 16^64 elements.
Now assuming I would like to just use the 3000 most-commonly used english words as input-parameters to the dat://-URL lookup App, then any of the possible 16^64 dat://-URLs could be assigned to any of the possible combinations of 23 of the 3000 most commonly used words in the english language.
Calculationnto get to this (the number 23):
16^64 = 3000^x
x = log3000(16^64) = 22,16