In my experience, that's mostly limited to movies, the only mainland Chinese and Hong Kong ones that are not all post-dubbed are generally those that are intended for export internationally and/or are art-house movies made by people that care about making the voices feel real, though most Chinese people don't care about this because they've been used to post-dubbing all their lives (and find it more distracting if characters in period movies don't sound old-fashioned enough or don't sound like they're all from the same place, which I didn't know about till reading this thread but it makes sense), and the major studio studios don't see the point when post-dubbing is much cheaper. The kind of Chinese movies one can find officially on ARROW, the Chinese Independent Film Archive, the Criterion Channel, BFI Player, dafilms.com, Filmdoo, Film Movement Plus, Icarus Films, Kino Now, MUBI, OVID, Projectr, Screeningroom, Viddsee and Vimeo tend to use voices recorded on set.
But if the original-language version of something is post-dubbed, by the original actors or voice actors, then there won't be a version with the on-set voices available anywhere, because they won't have been recorded, other than in making-of videos (avoiding the expense of recording them on set being one of the points of post-dubbing).
China isn't the only place where this practice is or has been standard. It's much the same case in India (though I think Indian movies tend to use the on-screen cast's voices except for singing) and it was the case for Italian films for much of the 20th century (which didn't bother so much with using the same cast for the visuals and audio, and a bit like Chinese ones had people speaking different languages on set and then dubbed them all into Italian for Italian audiences, English for English-speaking ones, and so on). Japanese tokusatsu TV programmes (and maybe other family live-action programmes, but I haven't seen much at all of any others) like the Ultra franchise and Super Sentai used to be all post-dubbed, but they transitioned to using on-set recording at different points in their histories (except for the monsters and when the characters have helmets on and are played by stunt doubles).
