Yes, with BackHub you can export a GitHub wiki.
A GitHub wiki is actually nothing more than a separate repository with markdown files containing your wiki pages. Wikis are included in the backup of your GitHub repository.
Here is a list of what is included in a GitHub repository backup.
First, create a full backup of your repository. If you haven’t already, follow the instructions on how to install BackHub. Once installed, wait until the backup of your GitHub repositories is completed.
After the backup is created, open the panel of the repository that contains the wiki to export. Click “Download Wiki”. If you have installed BackHub a while ago, you can choose from older snapshots.