The smart contract you build specifically needs the collateral token/coin to be on the same chain or network. That won't work for some lenders or borrowers. If I want to lend a bitcoin, how do you(the smart contract) make sure it stayed as it is, without wrapping it to another token, say, WBTC? it applies to another altcoin, Monero or anything that isn't tied to what the smart contract platform is built on.
Last but not least, as you stated by yourself that it is just the same as other lending platforms within defi, what makes your platform better than the others?
Yes, you are right. The only way would be to use wrapped tokens on the same blockchain network. I understand that from the perspective of bitcoin maximalists, PoS blockchains don't have enough trust with their censorship and anonymity issues. I'm not talking about decentralization since most of the tokens in "smart contract" blockchains are owned by a small group of people tightly connected to the project's founders. I'm just trying to build something useful with the resources that I have now. Because I believe that smart contracts are the future, even though we don't have a blockchain that we can all trust to.
The second question, the difference between other lending platforms such as MakerDAO or Aave is that they have strict policies on what collateral on what interest rate you can lend and borrow (pretty much like banks) and usually everything is contained in 1 smart contract, but in my mind, I have an idea where 2 people can create and deploy a lending smart contract with the terms that only both of them agree. I mean, without big web3 companies, they can deploy the separate contract only with the terms they mutually benefit from. For example, the minimum collateral in Oasis App is 175%, but I have seen in the bitcointalk some people are willing to accept collateral as low as 130%.