IMO a good place to start is factory cleaning, deployed internally...
They can then extend that to domestic cleaning, which is a app that would justify a Robot purchase for most people...
Speaking generically, I think cleaning is easier than FSD, but it still seems like a substantial development project.
Cleaning might initially be:-
- Dusting
- Vacuuming
- Cleaning empty benchtops
- Cleaning Windows
- Washing floors
The next upgrade might be:-
- Cleaning toilets, sinks and hand basins.
- Moving predefined objects
So it is possible they can avoid the need to recognise and move a lot of objects, by merely opting out of that initially.