iTextSharp.LGPLv2.Core is an unofficial port of the last LGPL version of the iTextSharp (V4.1.6) to .NET Core.
To install iTextSharp.LGPLv2.Core, run the following command in the Package Manager Console:
PM> Install-Package iTextSharp.LGPLv2.Core
You can also view the package page on NuGet.
The pdf is created, but when I try to view it, it says that the document is in use by another process.
You should dispose the FileStream/MemoryStream explicitly. It won't be closed and disposed automatically at the end.
I can't find what would be the equivalent of the PdfTextExtractor class.
PdfTextExtractor exists in v5.0.2+ with AGPL license (Current project is based on the iTextSharp 4.x, not 5.x).
It can't display Unicode characters.
You can find more samples about how to define and use Unicode fonts here.
To run this project on Linux, you will need to install libgdiplus too:
sudo apt-get update
sudo apt-get install libgdiplus
You have three license choices when it comes to iTextSharp: LGPL/MPL, AGPL, or a commercial license. The LGPL/MPL license is only an option with the older 4.1.6 version (used here). After that version, they switched to a dual AGPL/Commercial.
If you need a more recent version, you either have to make your project open-source or pay the license fee.