My search found the following spelling:
Nijisseiki pear
Nijisheiki pear

Your version is below. I suspect they are the same pear. If so, it appears “Nijisseiki” is the original Asian name for the pear that was re-named “20th Century” for marketing purposes in the USA … and 20th Century Asian Pear trees are for sale about everywhere. You could likely find a ‘bagged tree’ for under $10 at a local retail outlet. If not, move on to a more reputable local nursery, at likely twice the price.

If you’re concerned about height… just lop off it’s top anywhere down to (yet above) it's obvious graft union and force limbs at whatever height you want. And that’s something you could easily get away with while it’s young and newly transplanted.

Here’s something I found about the ‘two’ pears: “The 20th century Asian Apple Pear, or Nijisseiki pear, is just one of these fruits. It was introduced in 1898, cultivated from chance seedlings found in Matsudo City in Japan. Over the past century this green-yellow pear has become one of the most widely grown Asian Apple Pears in the world...”