What is the compatible Node version for Spartacus 4.X?

While Node 16 is not officially supported due to it not being supported in Angular 12, we have not encountered issues using Node 16 with Spartacus 4.x thus far. It will be officially supported in Angular 13/Spartacus 5.x.

Angular compatibility list: https://gist.github.com/LayZeeDK/c822cc812f75bb07b7c55d07ba2719b3

The package.json including Node 16:

"engines": {
    "node": ">=12 <17"
},