How can you build a model that reads out receipts and invoices?
You should start by trying OCR.  I am not sure why you are rejecting it without trying it. Start with Tesseract (free but not very good) and then try a commercial OCR as well (Abbyy is well regarded, but you could also try Adobe Acrobat).  Also, research document structure extraction.

That idea that you are going to re-invent a machine learning model that does OCR better than existing OCR solutions seems ... not very realistic.  Current OCR tools have years or decades of engineering put into them.  There is no way you are going to be able to afford to put that much effort into your own custom tool.

Image quality on those example images is not wonderful, and you might have to accept that accuracy will be less than 100%.