It is a file format
A .qbo file contains structured account and transaction data. It is not a QuickBooks company file and it does not contain your whole ledger.
Format guide
QBO is a QuickBooks Web Connect file format used to move bank transactions into supported QuickBooks workflows.
A .qbo file contains structured account and transaction data. It is not a QuickBooks company file and it does not contain your whole ledger.
A file can look like QBO and still fail an import because QuickBooks checks structure, account information, and financial institution details.
Before importing a file from any converter, make a backup and use a blank test company. Check dates, amounts, descriptions, and transaction count.
Intuit's Web Connect guidance explains common errors and why some files cannot be read or verified.