Many smartphones can be turned into a "hotspot" for use by other devices. Depending on your provider and plan, this may be either free or a small additional charge to your service. If you are unsure about your plan, contact your provider for details.
USAC (a funding branch of the FCC) offers a program called Lifeline which provides discounts to qualified families on their home Internet service. To find out more about this program, visit https://www.fcc.gov/consumers/guides/lifeline-support-affordable-communications