Roborock S8

It does not self-empty, so you empty the 400 mL onboard bin by hand and rinse the mop and fill the 300 mL water tank yourself.

The robot is 3.8 inches tall, so it slides under most sofas and cabinets, though very low furniture may be tight.

It clears obstacles up to 20 mm, so it handles standard door sills but may stop at taller thresholds.

Yes. It supports no-go zones and stores maps for up to 4 levels, so you can fence off rooms across floors.