The Innocn is currently one of the least expensive 4K 27-inch monitors you can find with full sRGB coverage, HDR400, FreeSync, PIP, and even a gravity sensor for switching between portrait and landscape orientations.
https://www.notebookcheck.net/Innocn-27-inch-4K-monitor-with-FreeSync-is-now-at-its-cheapest-for-just-280-USD.608540.0.html