These improvements will show up to non-Insiders soon. Typically Insiders on different channels will test latest code from:
Dev channel: latest code that passed tests inside Microsoft
Beta and release preview channels: latest code for the current Windows release
Build 22000.28x is the build being tested by Windows Insiders on beta and release preview channels, and it includes fixes for File Explorer. People on dev channel have already moved onto build 22400 series.
As for a possibly related question about NVDA supporting Windows Insider Preview builds: without going into details, yes, NVDA does support Insider Preview builds to some extent.
