You can use the Execute Command node in n8n to run Tesseract OCR locally. Just install Tesseract and Poppler on your n8n host, then chain it as: Read Binary File → Execute Command (OCR) → HTTP Request to Ollama. For multi-page PDFs, OCRmyPDF in a Docker sidecar is cleaner, and you can call it via HTTP Request node without touching the n8n host. Everything stays 100% local.
In general I found it a really nice pattern to deploy micro services in the docker network, which you then can just call with the https node (just use the name of the docker service as the baseURL). Happy to give you more information if you think this is a viable way for you.