why is the estimates not supported in import data? is there a faster way to fill in many item lines together other than entering a line after one?

Hello there, B2B-Team.

While importing estimates and filling in multiple item lines in QuickBooks Online (QBO) is currently unavailable, we encourage you to share your thoughts and suggestions with our Product Development Team by submitting feedback in QBO. This will help our product engineers understand how you would like the program to function.

Here's how:

1. Click the Gear icon in the upper-right corner.
2. Select Feedback under Profile.
3. Share your feedback.
4. Click Next to submit.

If you have further questions, click the Reply button below.

@B2B-Team 

You can use an importer tool.

https://get.transactionpro.com/qbo