The THETA V does not have HDMI output for live streaming. You would need some type of USB to HDMI converter. I do not have a good recommendation.
The THETA S does have HDMI output, but it is lower resolution.
The RICOH R Dev Kit does output HDMI. See the article below. However, it is lower resolution than the THETA V. Suggest you send a note to Ricoh and ask if they plan on updating the RICOH R Dev kit to the higher resolution.
Do you need the 4K live streaming for the focus group? Or is the 2K sufficient? Also note that there’s some hefty bandwidth requirements for 4K live streaming. Are you streaming to something like YouTube or Facebook?