Other than something based on Tesseract, I don't see many FOSS options

OCR (OCR based on Tesseract 5)

I personally use OSS Document Scanner.

It has different dictionaries, can scan docs/papers and archive them. Can also translate and extract text (to an extent). It works great for my needs, hopefully it is what you were looking for too

I use PDF converter by Swati Garg on F-droid

This is not a proper solution, but if you can't find an alternative that fills your need, you might try tracker control and use it to turn off internet access for google lens and see if it still works for your usecase. I think you have to search trackercontrol for it to show up on f-droid