When importing photos from an iPhone in Lightroom Classic, it would be valuable to limit the number of items shown on the import page to prevent freezing and to ensure thumbnails can be shown.
I have been using an iPhone for 10+ years and have 100,000+ photos on my iPhone. When trying to import photos from the iPhone, (on a MacBook Pro M2 Max with 32 Gb RAM) Lightroom cannot properly handle this number of photos. Limiting the number of photos, for example by paging, or by filtering on date, would likely solve this problem.