What could be a serious collateral?
I think it can be anything that party seems in value.
So maybe a ps4, or something that equals to how much your loaning. Its a way for them to sell it incase if you dont pay.
Physical items are not a good collateral for 2 reasons.
1. You need to actually ship the item to the lender or escrow, which will cost time and money. When you repay the loan, the item will need to shipped back to you, and the fee is probably on you again.
2. It is not easy for the lender or escrow to sell an used item like iPhone or ps4 (at least not as easy as some LTC), when the borrower can't pay back.
So, lenders usually prefer major altcoins as collateral.