The falcon 9 first stage cannot hover as the thrust of one Merlin engine even at its lowest thrust is able to overcome the mass of the almost-empty first stage. The stage appears to decelerate very slowly in the final moments of the landing as a result of the engine firing pattern SpaceX uses.
Per Elon Musk:
Thanks! 3 of 9 engines are lit initially, dropping to 1 near ground. Even w 1 lit, it can't hover, so always land at high g
- Elon Musk (@elonmusk) April 15, 2015
So as soon as the 3 engines are fired, the stage decelerates rapidly, but when the two outer ring engines are shut down for final approach, the deceleration of the stage slows rapidly, giving the illusion that it is hovering. Although this tweet is from early 2015, we know that the engines on the Falcon 9 have only gotten stronger, so it would have no chance of hovering. In order to land, SpaceX uses a hover-slam or suicide burn, so as soon as the stage reaches zero velocity while decelerating, it’s on the ground/ASDS. Blue Origin’s New Shepard rocket, however, can hover above the ground and does so to travel laterally before landing on the pad.