Seriously, good crypto should be limited and there is no way you are going to accept someone lending you bitcoin with a "bitcoin certificate". If you know your crypto bitcoin means bitcoin in your wallet address and with your own keys. There is no way you can borrow more than it exists if you have taken even the minimum required time to understand what you are doing.
Isnt el salvador chivo wallet, fractional reserve style wallet as long you are trading from chivo wallet to chivo wallet?
If that is true (the fractional reserve stuff would be used to give people their 30 dollars in BTC at chivo wallet, they are giving people to make sure they try it), people already accepted fractional reserve.