Does Vegas 16 pro allow adding 360 photos to the timeline alongside 360 video, to be rendered out for all to be interactive so user can pan around?

I’ve not kept up with Vegas and don’t know the answer to your questions.

Forced into Premiere a few years ago... I’ve edited lots of 360 stills/video content in Premiere Pro CC2018. The built-in VR extensions work very well for equirectangular 360 source materials.

Interactivity of looking around is something supported in players, not in editing. Youtube’s 360 player supports it. Headsets (head mounted displays, HMDs) support it.

For examples please see my recent thread http://www.dvinfo.net/forum/360-panoramic-spherical-ar-vr/536785-post-your-360-projects.html