How does this work practically for a US-based company? Since this is a remote work
visa, can they even physically work at a Korea-based office or subsidiary?
Also, there's a 17 hour time difference between Korea and Los Angeles.
It's Friday in US, but Saturday in Korea. On Monday in Korea, you have to wait until the next day for them to work. You only have 1h-2h before the work day in Korea to sync with them in US, only on the West Coast, only 4 days a week.
For “nomads”, I think the more common situation is that the nomad works roughly 2am to 10am Tuesday to Saturday, maybe shifted to 6am to 2pm for half day overlap.
Also, there's a 17 hour time difference between Korea and Los Angeles.