> Probably because it uses TensorFlow (lite) and there aren't many (any?) VPLs supporting C++ integration.

which VPL do not support C++ ? all the major ones have externals / plug-ins / modules that can be written in C++ - Max/MSP, PureData, LabVIEW, vuo, BluePrints, vvvv...

Google depends on thousands of external software projects.

They heavily support a VPL, Scratch.

AFAICT the relationship for Scratch is that Google wrote a new VPL (Blockly) and the MIT Media Lab released it as Scratch 3.0.

I guess the "thousands" is from https://opensource.google.com/? In a few minutes of browsing, I couldn't find anything besides Bullet that wasn't just Google releasing something as open source.

Python? Git?

Git is mainly for external consumption. They've got their own VCS called Piper that comes with a client called CitC (sit-see).