Thank you for your question. The concept of Wahdat al-Wujud refers to how there is only one essentially real being which is God. There are many differing views on the specifics of this theory which need to be fully explained within their field of study. As a conception in theoretical mysticism the theory doesn't have a sectarian bias. There have been Sunni and Shii intellectuals who have found the theory useful, as well as Sunni and Shii intellectuals who have rejected it.
May you always be successful