I build these robots (called UGV) along UAV and ROV for living.
And no, all of these food delivery robots are tele-operated remotely via cellular networks (not autonomous). The software usually are ROS-based and there are ready drivers for that type of work, along other sensors like stereo cams and visual cams, some even put 2D/3D Lidar, but the actual controls are happening by a real time operator with an Xbox/PS controller. Hardware wise, mostly uses SBC (nvidia jetson based mostly) and very few a small form factor NUC, although due to power consumption SBCs are the case, rest are the usual like relays etc. A coupe months ago, city of Toronto banned all these food delivery robots operating on pavements and cycle lanes in concerns of public safety and people with disabilities.[1]
[1]
https://cities-today.com/toronto-city-council-votes-to-ban-p...