Nextcloud OCR (optical character recoginition) processing for images and PDF with tesseract-ocr and OCRmyPDF brings OCR capability to your Nextcloud 10.
Please note that there are some caveats. For example you have to install extra software on your server
The OCR app does the pdf generation, but afaik it’s not happening automatically and there is not yet any mechanism that listens to an event like a new document event in a certain folder. The user still needs to manually trigger the OCR process manually via UI.
It would need to be implemented in a custom app that has a hook / event listener on new files in a certain folder (i.e. could be that the folder has a certain tag) and then start the OCR process.