Learning sight reading is the most natural on piano like instruments. The notes are literally arranged in the same order. Stringed instruments are much more difficult to learn sight reading from scratch on.
That's an odd take. Sight reading is about associating the mark on the paper with the actual note, duration, style etc. How that note gets played on a particular instrument is a different matter.
In fact, I never actually learned to sight read until I started on guitar. All I remembered from the old days was "all cows eat grass"