@petros What you need is to get rid of the PDFs and deploy an online store. 
What is the failure rate of the traditional OCRs compared to the LLMs? And how modern were those OCRs? Modern OCR in the last 5 years or so have a success rate way higher than 90%. And are the failures on OCR itself or interpreting their context (aka knowing how to read the invoice or order, not just identifying the right characters)?