Huawei already reinvented the wheel. Harmony OS is not Linux. It has its own proprietary micro kernel architecture. In comparison, Linux would already be an old legacy OS based on an ever expanding monolithic kernel. Let's just say that microkernel OS has fundamental advantages especially with regards to OS maintenance, security and latency, which can be of great benefit when it comes to scaling (server, cloud, supercomputing) and IOT.
In fact, Harmony OS has great potential for everything IOT from TV to smart automobiles. It might be the most ground breaking development with Chinese IT sector yet that can lead to OS independence from the west, and one that can go beyond borders.
Even creating your own instruction set should not be too hard. That wheel has also been reinvented for the Chinese supercomputers years ago. Legacy instruction sets like MIPS, SPARC, ARM and X86 are their own performance bottleneck.
Huawei doesn't need US government pressure to develop their own operating system. They already started long ago in order for Harmony OS to be able to reach this stage where it is already real world applicable. Even though it was unveiled in 2019, development for that would have taken place years ago given the advanced state of the OS, since it was already deployed in Huawei and Honor smart TVs.
Where Huawei saw the writing on the wall was when Google was developing its own Fuschia OS. Fuschia would be the replacement of Android and ChromeOS, and despite saying that Fuschia uses the open source Zircon microkernel, I doubt that Fuschia would be as open as Android was, which is in turn isn't as open as Linux (for those who don't understand this, Android uses the Linux kernel.) That means those who depend on open source Android --- Android without GMS --- like Amazon and the Chinese mobile industry --- are going to get screwed when Fuschia comes out. Ironically, the first devices Fuschia was tested on was certain Huawei devices. (People forget that the last Google Nexus prior to the first Pixel, was made by Huawei, but Fuschia was also tested on non Nexus Huawei devices.)
Having said this, Samsung has been trying to do its own OS, first called Bada, then Tizen, without much commercial success except for smart TVs and smartwatches. So how can Huawei succeed when a giant like Samsung has failed. The answer is that Samsung doesn't have a huge captive domestic market like Huawei has. The most brilliant development in the history of Chinese IT --- and the biggest mistake Google has ever made --- was to voluntarily leave the Chinese market because Sergey Brin --- with vocal opposition from Eric Schmidt to the point of having shouting matches --- didn't agree on manually censoring search results to meet Chinese government requirements. Something that Apple and Microsoft had no problem doing. This enabled the development of an entire Chinese software ecosystem that is non Google dependent.