Buddhism could theoretically work, but the main issue is that it is currently split between the Mahayana and Theravada branches. Most of the individuals who believe in the former believe that Buddha himself is a "god," while the latter tends to view him as a human being who achieved enlightenment. There are exceptions, however, as my sect does not acknowledge Siddhartha Gautama as a "god," even though it is technically derived from another Mahayana sect. There are also other various "human beings" and "gods," depending on the sect involved, but Buddhism is more of a philosophy than a religion, and it managed to syncretize with other various beliefs, such as animism.
In order to make the proposed scenario work, you would probably need to focus more on the "enlightenment" part, such as what occurred in the Theraveda branch in Southeast Asia, or more philosophical ones in the Mahayana branch, such as Chan/Seon/Zen. However, the biggest issue with this is that it requires individuals to sever ties to society, along with seclusion to a certain extent, which is extremely undesirable for the government. This was one of the reasons why the Tang persecuted Buddhists, as it viewed them as corrupt monks who earned money without paying taxes, while the Mahayana branch later allowed laymen to comprehend most of the core tenets.