Can a House Sitter just spend day at house or does it need to be overnight?

Yes. During the meet & greet (or before) you definitely should discuss your needs&wishes with the sitter and specify the amount of time you want/expect the sitter to stay there.

Rover allows the flexibility for pet parents and sitters to agree on care that may differ from their recommended guidelines, so often the services offered by sitters are quite different. This can be booked a variety of ways after you reach agreement with the desired sitter to provide care at your home if that's what you prefer.

As a general guideline, House Sitting covers up to 24 hours and Day Care is usually about 9 hours. https://support.rover.com/hc/en-us/ar...