I have a rather stupid PoD, but why not.
In OTL :
My PoD would be to have a crippled Zheng Kezang survive the coup against him and defect to the Qing, joining Shi Lang before the battle of Penghu Islands fearing for his life and thirsty for revenge.
His presence on the side of the Qing causes the defection of Liu Guoxan and the majority of the Tungning fleet surrenders without fighting. With the treason of Liu's fleet, Penghu surrendered and Tungning soldiers deserted in droves. It became obvious to the court on Taiwan that they were now defenceless.
Zheng Kezang landed on the island with Qing troops and Liu Guoxan’s soldiers. Zheng Keshuang quickly gave in to the his brother’s demand for surrender. Following this surrender, Zheng Kezang negotiated the survivors’ fate with Shi Lang and publicly executed Zheng Cong (鄭聰), Zheng
Dexiao (鄭得瀟), Hung Liangji (黃良驥), Xiao Wu (蕭武) and Hong Gongzhu (洪拱柱). He was subsequently taken to Beijing to meet the Kangxi Emperor.
During this meeting, he persuaded the Emperor to turn Taiwan into a province, explaining that an autonomous province wouldn’t become an economic burden for the Empire and could be self-sufficient through trade, thanks to Hokkien maritime trade network and a number of sojourning communities overseas. He promised to share the control of this province with Shi Lang and asked for the presence of Qing soldiers on the island for his own protection against the remaining Ming loyalists. He also swore not to marry.
To ensure Zheng Kezang’s loyality, Zheng Keshuang was taken to Beijing, where he was ennobled by the Qing Emperor as "Duke of Haicheng" (海澄公); together with his family and leading officers, he was also inducted into the Eight Banners. Junior members of the House of Koxinga acquired the hereditary style of Sia (舍).
In 1684, Taiwan was divided into three counties and established as a province. Zheng Kezang increased the administrative regions on the island to twelve counties in order to tighten control on land and to reduce crime. In agreement with Yongzhen Emperor, he implemented land reforms and simplified the Qing land management. As a result of the land reform, the taxation received by the government increased by more than threefold. He also developed the mountain area to promote harmony between the migrants and the Indigenous Taiwanese peoples.
Chinese pioneers, however, were constantly pushing the bounds of Chinese settlement northward and eastward and the aborigines were forced to adapt. Individual entrepreneurs or land companies usually organized Chinese pioneering enterprises. These people obtained land from aborigines or the government, recruited settlers, supplied loans to the settlers and sometimes invested in irrigation projects.
Zheng Kezang died in 1750 at the venerable age of 87 years old, ending the eight decades of rule by Zheng family. During his reign, the population of the island grew exponentially and Taiwanese kongsi in South East Asia became one of the main income source of the Qing Empire before the reign of Qianlong.
This economic success pushed the Qianlong Emperor to invest into a merchant fleet and to improve the naval defenses of the country. He authorized Zheng Kezang to create a Chinese chartered company and allowed him to adopt an orphan as his son in 1745. This son became the next governor of Taiwan and was in charge of the protection of a vast network of Chinese outposts from Malacca to Japan.
Under his own governorship, Chinese traders opened trade posts in Arabia and on the African coasts. A Chinese merchant mapped the northern coast of Australia in 1783.
To be continued if you like it...