[paragraft]

Those limitations apply to the old model of App Engine they call the Standard Environment, which abstracted much more over the underlying resources (you didn't have to think about what VMs you were using).

At some point they realised that maintaining their own parallel forks of the runtimes was a loser's game and now gently push you toward the "Flexible Environment", which maps more transparently onto GCE (their equivalent to EC2) instances (which is better for them since you're billed much more directly according to your resource use), and has much more up to date runtimes, and you can supply your own docker image if none of them fit.

The only people I know of who actively use the Standard Env anymore for new projects are trying to have a hobby project run for free in the free tier.