I'm a retired real estate broker in Westchester. Your 1st step is speak with a mortgage lender and get pre-approved. Licensed real estate agents & brokers will ask to see your pre-approval BEFORE showing you any properties. Realtors need to know what price range you can afford. Bear in mind property taxes are high and you will need property insurance.
As for your wheelchair, most doorways in private homes are less than the width of a wheelchair. Your best strategy is use a licensed experienced realtor & explain your preference should be ranch homes and doorway entrances to bathrooms & bedrooms must have a minimum width for wheelchair access.
Please keep your search area wide because you will be limited with accessability and request a bedroom on the main floor.