The past two nights I left the 'indoor walking' activity going all night on the Venu 2s. The result is that no sleep data is being show in Garmin Connect for those two nights. I did the same all last week with the Venu SQ (also running indoor walking all night), and didn't have it interfere with the sleep data.
I'm working on a sleep related app, and have been using some datafields for testing. I haven't yet checked whether running any app is impacted, or just activities.