[mk89]

You can make debt, as many governments have been doing until now...

And debt (spending) ironically will increase the GDP.

If a company keeps on producing goods and doesn't sell them? That increases also the GDP. ( as long as they don't throw them away )

If a government makes debt to buy weapons and increase the army? Look at the Russian +4% GDP just because of that. However, how sustainable is that? The GDP doesn't care at all about that.

The GDP doesn't provide the full picture of how a country is doing economically, but it's good to have a first overview to later do a deep dive into, but so are other "tools".

It's an old tool created 100 years ago, and we keep on using it although the world has changed drastically since then.