I finally got my Raspberry Pi Zero 2 W. 

It has the same Conrtex A53 as the 3A+, so I knew it would work, but I just replaced it and it worked as is. I was worried that the clock frequency would drop from 1.4GHz to 1GHz, which would slow down the processing speed, but it is within 1.2 times that of the 3A+, so there is no problem with the mowing operation. Also, the heat generation seems to have decreased. The only thing that bothers me is that the USB input is microUSB, so I have to connect my webcam via an adapter. There is no audio jack, so to make the robot talk, I have to think of a way to deal with it.