if a business decides to accept bitcoin as payment or collateral for a loan, then they will have access to a wallet(which can verify messages).. so they will know enough about bitcoin to participate by just using most wallets..so not really a problem that needs solving
If you read carefully what I wrote, i'm not speaking of payment or collateral. In both cases, indeed, you need to transfert your bitcoin. I'm speaking of proving your weatlh to someone