Everyone has the essence and nature of Buddha… Jodo Shu neither denies nor actively teaches this.
Even if we have the Buddha Nature in us, it is covered with a thick layer of our worldly desires. Buddha Nature cannot appear through Gateway of the Holy Path in this defiled world. Only in the Pure Land in the afterlife can it appear. Therefore, Master Shan-tao and Honen Shonin hardly referred to Buddha Nature as the possibility of attainment of Buddhahood (in the present life). Some of Honen's disciples, Shoku, Kosai and Shinran, referred to Buddha Nature in the context of Pure Land Way.
I don't know about dharma of Emptiness taught by Master Shan-tao or Honen Shonin. However I don't think that teachings of Jodo Shu are unrelated to Emptiness.
In my humble opinion, dharma of Emptiness could be considered from two aspects.
One aspect is the realization and direct experience of Emptiness. From the Jodo Shu perspective, we can truly realize Emptiness, the ultimate enlightenment only in the Pure Land. The daily practice of Nembutsu will lead us to the realization of Emptiness after our Birth in the Pure Land.
The other aspect from which we can consider Emptiness is the teaching of non-attachment. The main point of dharma of Emptiness is non-attachment. Like the following.
"Everything is changing and non-substantial. Let your attachment go, and you will be liberated from your sufferings. "
In this aspect of teaching, we wish to be born in the Pure Land on the assumption that we have been living in the defiled world of transmigration, and also we ourselves have been ignorant, sinful persons. This perspective of Pure Land Way is in common with the teaching of Emptiness and non-attachment.
Thus, we may be able to understand the relevance between dharma of Emptiness and the teachings of Jodo Shu from two aspects.
In Jodo Shu teachings, Amida Buddha is regarded as a buddha of Sambhogakaya, not a buddha of Dharmakaya. As you know, when Amida was a bodhisattva, he made the 48 vows for the salvation of all sentient beings, practiced austerities and attained the supreme enlightenment. Therefore, it is natural to regard Him as a buddha of Sambhogakaya. Tao-cho, Shan-tao and Honen Shonin adopted this theory that Amida is a buddha of Sambhogakaya.
On the other hand, Honen Shonin also says that in the enlightenment of Amida Trikaya, He become one as in the enlightenment of any other buddha.
Although there are various theories, when we return to the basics of Mahayana, it is most important to emphasize that even after Sakyamuni passed away, a buddha who has eternal life always exists and guides us to relief forever. There is no need to deeply involve ourselves in the theories of Trikaya. That is my frank opinion.