I am doing a writing challenge for my self and wanted to do this very thing. I want to print and bind how much I accomplish in writing each year. It's one thing to write stuff and virtually hide it away, but I want a physical copy for posterity. My plan was to tag things in sets: Cooking, Technical, Literature, etc. and make a volume for each. I am pretty clever, so I could probably implement this with pandoc, but it would be useful native wiki.js feature.

Is there any workaround to export the entire wiki in one single document?

I'm very interested in this feature as well

I'd love to see this capability as well. Currently I do product documentation through MediaWiki, but am migrating to wiki.js now. The only thing missing is the ability to create an 'offline' manual in PDF format, which is something that can be done (Albeit in a bit of a messy way) with MediaWiki.

with the git backend you can set up a CI pipeline to automatically generate a portable version of your wiki. e.g. you could use pandoc (https://pandoc.org/) to generate almost any format you want, including PDF.

The only issue here is that the git backend only receives the text files, and any assets in the wiki (e.g. images) will be lost. However, I've added a request for the storage backends to receive all assets: https://wiki.js.org/feedback/p/storage-modules-should-receive-assets