I can help share some information about the data you can import in QuickBooks Online, g-acc-daiso-sang.
Here's the list that you can import to QBO:
Bank Data
Customers
Vendors Chart of Accounts
Products and Services
Invoices
When importing a general ledger, you can only bring in account balance and details. You'll want to enter the transactions manually in QuickBooks Online.
Here are importing data-related articles for additional reference and guide: