This is previous work. Bolt3D uses the same principle, of predicting a per-pixel Gaussian splatting representation but it also trains a diffusion model, which is only feasible if you have substantial compute available.
Given that it's a work done at Google I will not expect them to release source code. But it will be reproduced by someone else soon enough.
This is a previous paper/work by the lead author a year before they interned at Google Research and produced Bolt3D.
Bolt3D appears to be his intern research project done in conjunction with a bunch of other Google and DeepMind researchers.
I don't suspect there will ever be publicly available code for this.