I think it's purely software translation from x64 -> ARM.

I think the question is whether the performance will be reasonable. Most emulators (e.g. of gaming consoles) struggle to keep up with recent software, since the translation often incurs in a lot of overhead.

Game emulators are running everything emulated. An application running on top of an operating system will hopefully get some benefit of spending time calling native operating system code. It helped a lot back in the day with Apple’s 68K to PPC transition.

Ideally "recent" software that's performance needy will offer native binaries. Emulation is to support the long line of not-recent software

It’s just dynamic binary translation. It isn’t a full system emulator. It works fine for many other implementations.

I assume it's targeted at consumers. Many of them are happy right now with Windows on old Core 2 Duo, Celeron, etc, machines. Assuming a sufficiently fast ARM processor, they may not notice the slowness the same way you would.