On few occasions when I get to this step on most fiat online casinos around my country, what I often used as source of funds could range from statement of account from banks.
My question is can we use crypto wallet with long history of transactions and possibly a sign message be used as source of funds requirements for online crypto casinos?
The source of funds would need an origin from which the cryptocurrencies are getting deposited to yout wallet.
Simply providing the wallet transaction won't do any good until it's actually showing the true origin of those funds.
For example: if you are getting paid in bitcoin from then your wallet should show that particular transfer.
Also, if you are receiving funds from an illicit source or if any of your transactions are flagged then you might get in trouble as the source of funds is not genuine.