If there ever was such a suggestion it is unlikely anyone in the Qing inner circle seriously entertained it. This is because you have to think of the Great Qing as not just being China, but in fact a larger imperial entity with both Inner Asian and Chinese components, and where although the material strength of the Chinese component was recognised, as an ideological whole the empire did not bow solely to Chinese interests.

The crucial thing is that the Qing Empire encompassed a hugely religiously pluralistic range of territories. The Han were Confucians, Buddhists, Daoists and, most of all, believers in folk religions; the southwestern and Taiwanese aboriginal peoples had their own folk traditions; the Hui were largely orthodox Sunnis; so too the Turkic people of Tarim, albeit with a substantial Sufi presence; the Mongols were Tibetan Buddhist; the Tibetans go without saying; the Manchus themselves were Tengris; and for many decades the Qing actively tolerated the presence of Jesuit and Orthodox missionaries. Each religious context demanded a different approach: for example, the inner Qing court maintained shamanic rituals as per its Manchu heritage, sponsored Buddhist hero-cults to appeal to Tibetans and Mongolians, and projected their Confucian acculturation to the Han Chinese.

The Kangxi Emperor's Sacred Edict needs to be understood in that lattermost context: as an appeal to Han Chinese sensibilities at a time when the legitimacy of Manchu rule in China was still somewhat questionable. Out on the steppes, the Kangxi Emperor was a pretty bog-standard Inner Asian warlord, the extent of whose power could only go as far as his armies could march – and deep into Mongolia they did. And he was hardly unaware of the value of appeals to Tibetan Buddhism, as one of the last major military actions of his reign was the expulsion of the Zunghars from Tibet in 1718-20.

The crucial thing to say here is that even Qing emperors themselves were not religiously monolithic. While the Kangxi Emperor projected an air of Confucian sensibility, he was still an active sponsor of Tibetan Buddhism and a regular participant in Manchu shamanic rites. The Qianlong Emperor especially has been argued by some to have been devoutly Buddhist even while maintaining the trappings of a Neo-Confucian state in China. Some older perspectives in the late '90s, exemplified by Pamela Crossley in A Translucent Mirror, argued that the fundamental incompatibility of Neo-Confucian and Buddhist political philosophy meant that any ruler who adopted both styles could not be either, although as stated, more recent perspectives suggest that the Qianlong Emperor at least was likely a personal believer in Buddhism to an extent (though I myself have usually erred toward a more cynical view).