The microchip miniature atomic clocks are not optical atomic clocks, but old-school microwave atomic clocks.

They are orders of magnitude less accurate than even portable optical atomic clocks and the difference is much greater in comparison with SOTA laboratory cesium clocks or hydrogen masers, which are again orders of magnitude less stable than the best laboratory optical atomic clocks.

However, these miniature atomic clocks are much smaller and cheaper than better atomic clocks and there are applications where something better than an OCXO-based quartz clock is desired.