20% in Euro of Crypto value.
This is not clear at all.
Math tells that this 20% is not the interest.
Then what's that? 20k EUR is 20% of your crypto holdings worth, meaning that you plan to put on escrow crypto that today worth ~100k EUR?
Also the way the fiat is transferred needs to be also cleared up, but that would be the second point. First you have to prove you have plenty of collateral.
That's exactly what I mean. I put about 100k€ of crypto as collateral. Transfer as normal SEPA transfer. 100k in crypto just in case crypto price goes down.
Coins as collateral, 2BTC, 5000 Tezos, 80 ETH, some LTC and cardano, total price of all crypto in today's price 100k€.
You might be interested in looking at defi if you can't get anything here. The 5% interest rate seems quite low to try to long the euro but you might find someone who can take the deal...