Hi @Sanja ! PM from the Office Scripts team here - opening a second workbook isn't possible through Office Scripts, but depending on your scenario you might be able to do this with a combination of Office Scripts and Power Automate. As an example, here's a scenario that uses the two technologies to combine data from multiple workbooks into one workbook: https://learn.microsoft.com/en-us/office/dev/scripts/resources/samples/combine-worksheets-into-single-workbook.
I hope this helps! Please feel free to reach out with any other questions.
Cheers,
Nancy