If you are looking for open source solutions, your options can be, not limited to, Ghostscript (to convert pdf page to image), Tesseract or PaddleOCR (to run OCR on the image). All can be installed on Windows, and be invoked from python script.

If you want to save effort to write python script, you can try PdfOCRer available in GitHub, which takes a PDF (possibly non-searchable), process it and output a searchable PDF.