Yes and no.
TL;DR Just sit on your seat and try to speak as low as possible to best avoid disturbing others. Be prepared for environmental problems, however, like bad network and ambient noise.
To clarify, by "is frowned upon" in the previous answer I meant "people dislike it", not "there are rules governing that you shouldn't do it". Only until recently have "quiet carriages" been added where generating loud noise will be punished with fine. And this "quiet carriage" isn't domestically available, only on some selected routes.
So Yes means there are places where you can both have network connectivity and be allowed to talk aloud, by buying a ticket for a "non-quiet carriage". You theoretically can make an audio/video conference on-the-go.
Now it's time for the However. I'll repeat my words from the last answer:
This is definitely not going to bring your audio/video conference to a success.
Caveat emptor, the on-train Wi-Fi is merely usable. You may have some luck with your cellular data, but since the train Wi-Fi is already backed up by optimized 5G network, it's uncommon that your cellular data performs better.
The other thing to note is noise. People playing TikTok or other media loud from phones has always been a hot complaint before it's banned in city subways. While not as prevalent on high-speed railways, this is intermittently a problem, a real problem. Noise-cancelling headsets may provide some help, though.
Finally, if you have an abundant budget, buy a ticket for a business-class seat where you can have a comfortable seat and a wide opening for your stuff. It's more likely others will complain loudly, however, as there's only a handful number of business-class seats on one train (12 to 15) and people buy this expensive ticket only for a pleasant trip. Again, speak as low as possible to best avoid disturbing others.
The internal of a business-class carriage, image belongs to public domain