So lenders don’t offer loans under $500 only because this won’t be profitable for them?
That's the truth, most of them has high loan minimum amount. I don't have a company to suggest but does your country does have small cooperative that offers low loanable amount? you just need to provide them valid requirements that you're earning with something or a valid collateral. I doubt it that type of institution will allow you to borrow by just providing bitcoin as your collateral. If you're going to use it as collateral why not just sell it?