If it is not going to be a regularly scheduled loan with interest,
you can just create a cash asset account. Transfer money to the
account when you lend it, and transfer money from there to checking
when you get repaid.
If you choose, you can call the account an Asset account. Then it
will be listed under Assets rather than Bank Accounts.
However, yes, you can avoid creating an account. You could create an
EXPENSE of PersonalLoan:John. If/when John pays you back, you could
use that same expense category for the deposit to checking; ignore
the warning about using an expense category for a deposit. You could
customize a report to get the information you want. Save the
customized report as a Favorite report.
You could customize the Transactions By Payee and select only payee
John. Select all dates. The grand total will be the negative of what
John still owes. Other reports should work, and you might find one
that will serve as a better starting point.