Not everyone ran to #vanlife as happy as a hippie – sometimes economic or other pressures force one into living in their vehicle. In this situation we are focused on functional, not fancy.
First things first, let's reframe the situation a little bit. These perspectives may help you cope with the new stresses:
You will need a place to sleep. Many people recommend earplugs and eye mask to block out light from streetlights, headlights, etc. Your first few nights in the vehicle will likely be rough as you get used to the idea.
You will need a place to pee. A gatorade bottle or similar is common. Women may want to use wider-mouth jars. You will also need a place to poop. With any luck you will have access to a public restroom. If not, a couple grocery bags (doubled up) will do; tie off and dispose of in the trash. You might also dig a cathole if you are in a place with grass or soil. If you have room, a bucket makes the process more comfortable.
You will need water to drink, to clean the vehicle and yourself up. Empty soda bottles are tough and hold water well. Rinse them out and fill in water fountains, spigots, sinks, whatever. If you have space to store gallon or larger jugs, water refill kiosks are relatively inexpensive.
You will need food to eat. Fast food is extremely expensive. Sandwiches made from deli supplies will be inexpensive. Since you probably won't be able to cook yet, focus on foods that can be eaten cold. You'll need a good can opener in any case. Peanut butter is a great bang-for-buck. Since you likely will not have a fridge, leftovers should be kept to a minimum. Buy only what you can eat.
You will need a way to dispose of trash. Stuff trash inside other pieces of trash; loose bits inside jars and cans, for example. Toss trash into receptacles whenever possible.
You will need a place to park for the night. If you are in a city this typically means stealth camping. If you are on the highway you can usually sleep in a rest area then move on. In rural areas (particularly out west) you may be able to boondock.
If you don't have a mobile data plan on your phone you can use public wifi to for internet. Even though libraries, cafes, etc, are closed they likely still have wifi in the parking lot. Note that with some open wifi systems you have to connect to an unsecure website like http://m.cnn.com (not https) in order to get the connection agreement to show up so you can click on it.
For privacy, you can use a sunscreen in your front windshield and cut-to-shape cardboard (preferably dark or painted) on side windows. Hanging clothes up in the window is a sure giveaway.
For power, most charging for small devices like phones and tablets will be by USB. Some newer vehicles have USB jacks built in. If not, you can find ones that fit into the cigarette lighter in dollar stores and similar. Charge as often as you can, preferably while driving. See this discussion of power options.
If you will be going to work or public indoor space regularly a small battery pack and extension cord may serve you well.
If you don't have a license or photo ID get that immediately, as a lot of other things depend on it.
If you have a car note, pay that first and insurance first. You don't want your home to get repoed!
Register for social services in your area as quickly as possible, as there can be some lag. Food banks, unemployment, food stamps, etc, they exist for precisely this reason. They were funded by you and by people like you for situations just like this. Don't be a hero or a proud idiot.
If you still are going to work, do as much of your device updating, bathroom-using, washing-up, trash disposal, ice-making, water collection there as is appropriate. Example: rotate in freezer packs when you get to work and put them back in your cooler at the end of the workday.