In iCloud Photos, I find it very useful that in my massive photo library I can search for text appearing in my photos. This makes searching for old pictures of documents (like a business card from three years ago) very easy. Optical Character Recognition (OCR), from my understanding, is much less computationally intensive than image classification or facial recognition, so it would be easier to implement before those in Proton Drive to scan your library and easier to run via local models, and still add a lot in terms of search functionality.