2 to 4cm can be easily removed; hair is removed well (we have a long-haired German shepherd, perfect cleaning).

Hi Sarah, it gets over doorsteps without any problem. The Roborock regularly climbs over our dining table chair legs (swing chairs). It also tries our skid-like sofa legs, gets stuck at the 15cm height.
Long hair is no problem. But be prepared for regular cleaning of the brushes.

Dear Sarah, unfortunately I can't tell you much about the doorstep, but we have a deep pile carpet and he gets over it very well. LG Tanja