If these vinyl areas don’t include the seats, then I would use Lemon Pledge. The lemon oil in the Pledge would be left behind on the vinyl to prevent it from drying out. But don’t spray the Pledge directly on the vinyl such as the dash. Otherwise the inside of windshield can get coated with this lemon oil. Instead, spray it into a cloth and wipe the area down.
As far as washer fluid, it just contains distilled water, some methyl alcohol, and some blue dye. If you live where the temperature doesn’t drop below freezing, you can get by with plain distilled water.
Tester