Hi there, luvmytrk.
I'm here to share some information about importing payroll data into QuickBooks Online using Excel spreadsheet.
As of now, this option is unavailable in QuickBooks Online. As a workaround, yes, you can provide them an Excel file and use it as a guide in entering the data manually.
To do this, they'll have to enter them using a Journal entry. Before doing so, I'd recommend reaching out to their accountant so they'll be guided further.
I've added this reference as their guide in entering payroll details: Manually enter payroll checks.
Apart from this, they can also look for an application integrated with QuickBooks that can import their data. They may check this link to see the available apps: QuickBooks Online Apps.
You may also visit our Help Articles page for more guides in managing QuickBooks data: QuickBooks Online Q & A.
I'll be around if you or your client has questions about payroll. I've got you covered!