How Long Does It Take to Fix 10,000 Photos?
Usually well under an hour on an ordinary computer, and longer if you are converting HEIC or videos.
Writing dates and coordinates is quick work. On an ordinary laptop with an SSD, ten thousand photos is typically ten to thirty minutes. The disk is usually the limit, not the processor.
Converting HEIC to JPG or rebuilding videos as MP4 is real work and takes longer. Looking up place names adds time too, because each lookup goes over the network.
Takeout JSON Metadata Fixer shows a progress ring and a live count, so you can see the rate within the first minute and judge the wait for yourself. It runs on your own computer and is free for your first 500 photos.