COLMAP to generate pose data using structure-from-motion; if you use Nerfstudio to make your splat (using Splatfacto method) it includes a command that will do the COLMAP alignment. This definitely is a weak spot though and a lot goes wrong in the alignment process unless you have a smooth walkthrough video of your subject with no other moving objects.
On iPhone, Scaniverse (owned by Niantic) produces splats far more accurately than splatting from 2D video/images, because it uses LiDAR to gather the depth information needed for good alignment. I think even on older iPhones without LiDAR, it’s able to estimate depth if the phone has multiple camera lenses. Like ryandamm said above, the main issue seems to be low value/demand for novel technology like this. Most of the use cases I can think of (real estate? shopping?) are usually better served with 2D videos and imagery.
On iPhone, Scaniverse (owned by Niantic) produces splats far more accurately than splatting from 2D video/images, because it uses LiDAR to gather the depth information needed for good alignment. I think even on older iPhones without LiDAR, it’s able to estimate depth if the phone has multiple camera lenses. Like ryandamm said above, the main issue seems to be low value/demand for novel technology like this. Most of the use cases I can think of (real estate? shopping?) are usually better served with 2D videos and imagery.