Currently, there is no ocr. I also don’t know if I’ll add at some point in the future. It kinda clashes with the philosophy of keeping it simple and minimal as it is quite resource hungry.
I just checked, I usually don’t use the app on a mobile device. If you want to highlight text on mobile:
There is not much I can do as this functionality is provided by mozilla’s pdf.js library (this also powers the pdf reader of firefox).