But the article shows that the Nvidia ecosystem isn't that mature either on the DGX Spark with ARM64. I wonder if Nvidia is still ahead for such use cases, all things considered.
On the DGX Spark, yes. On ARM64, Nvidia has been shipping drivers for years now. The rest of the Linux ecosystem is going to be the problem, most distros and projects don't have anywhere near the incentive Nvidia does to treat ARM like a first-class citizen.