>>339958037
is the platform moving purely sideways in the XZ plane? you might be able to jiggle it slightly upward and back down in the animation to get the unity character collider (and thus your viewpoint) to move.

For a robust solution you'll have to put VRCStations (aka seats) on the platform and have people sit in them to move with the platform. Kind of annoying but it's pretty much the best you can do with vrchat at the moment.