It seems like a charming theory, but it only works when applied to the US dollar. If any other country decided to simply print money to fund their government budget, they’d quickly run into hyperinflation.

This is not true at all. Hyperinflation is very rare and only happens under specific, known conditions. It’s quite avoidable, except if you’re a small country that the US is trying to regime change, in which case all bets are off. PEGS Institute: What Caused Hyperinflation In Weimar, Zimbabwe And Venezuela?

It’s not like the US is the sole country with fiat monetary sovereignty today; there are quite a few.

Here’s a copypasta from a comment of mine on a post about China’s economy:

[George Soros] later admitted in 2001, that the local monetary authorities did a good job in preventing the collapse of the Hong Kong market. The precise way that China avoided this speculatory attack was through its strict state-set capital controls and its state-owned financial system

To use the metric of return on assets (ROA) and liquidity ratios to measure the effectiveness of China’s state-owned banking system is ultimately meaningless. This is because Chinese banks take on the means primarily resembling development banks. In turn, this system has an overall positive impact in the long term, despite not having the myopic short termism of Western commercial profit-oriented banks. This is due to the ability of long-term funding at low interest rates being key for the sake of large-scale infrastructure construction, which in turn is vital for long term economic development.

The reason why China’s economy is able to be stable and avoid the damages of the Great Financial Crisis of 2008 and the COVID Crisis of 2020 was precisely because it was able to draw up large amounts of State investment to offset the decline in private investment.

MMT isn’t a politics and isn’t prescriptive. It’s simply descriptive of fiat monetary sovereignty. Many liberal proponents and detractors alike seem to want to load up MMT with all sorts of things that it isn’t. It certainly isn’t going to solve all of capitalism’s internal contradictions under a dictatorship of the bourgeoisie. But China seems to be showcasing its veracity.

As I have understood it, private banks are also involved in money creation, as the interest they charge on loans is considered “new money.”

That doesn’t make any sense. The interest I owe on my loan is the opposite of money: it’s a hole I’m obligated to fill with money. It means I have to acquire money from somewhere, somehow to pay that interest or else default on my loan. In this sense, private banks are a drain on the economy, especially since almost all of the loans are for speculation rather than investment in industrial capacity. The neoliberal financialization of the US and other countries is creating debt deflation. No one can spend money because we’re laden with debt, interest charges, and late fees; and no one can get decent jobs because no one is spending money. That’s what Michael Hudson’s Killing the Host is about (PDF).