Transformation in the Tianhe Realm, without discussing resources, is much more difficult than on the Immortal Gate side.
Taishi Weiguang is quite a character, the Flying Sand Sect was also one of the Halls of Ten Directions during the Eastern Emperor Court times, but there's no mention of any Dao Fruit, and even if there were Deity Transformation Pills, they must have been used by the Nascent Soul Cultivators of that time after the death of the Sand Ancestor.
Previously, the Flying Sand Sect had also inquired about Deity Transformation Pills from the major Holy Lands of the Eastern Continent, but even with their most precious Five Direction Divine Sand, it wasn't valuable enough for exchange, so naturally, all the Holy Lands refused.
Without Dao Fruit and Pills, relying solely on one's own foundation to achieve Divinity Transformation is a slim hope, even Chen Mobai feels it's overstated to say there's a ten percent chance.
