> That being said, I believe if more subtags from `*-Latn` to `*-Latn-pinyin` is specified, using `cmn` would be wise anyway. `zh` is only needed for compatibility at a simple level.

Negative. BCP 47 only allow either `bo-Latn` or `zh-Latn` to be the prefix of `pinyin`

%%
Type: variant
Subtag: pinyin
Description: Pinyin romanization
Added: 2008-10-14
Prefix: zh-Latn
Prefix: bo-Latn
%%

https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry