I leave you these two links to read up on the subject, so you are able to understand how it works.
I think it's quite easy as a process and certainly does not require a loan or use a wallet as collateral .

https://bitcoincore.org/en/doc/0.16.0/rpc/wallet/dumpprivkey/
https://bitcoinelectrum.com/importing-your-private-keys-into-electrum/

generally speaking providing a wallet as a collateral it's kind of silly proposal as you can easily understand ...