Just keeping tabs on who is doing what in govt makes you way more informed for elections. Speaking out for things you want to see/change can sway how things turn out.
Federal govt gets all the focus (especially lately) but for a lot of things state and local govt is where it's at. For example marijuana is STILL illegal on a federal level but more and more states are fine with it. Gun laws seem to have had a lot of change on a state level too.
For my area local (city/township) govt runs fire, ems, small business initiatives, zoning and events. County govt runs minor road maintenance, emergency management, hazmat/drone stuff etc.
And state govt does a ton of major road work, big picture planning and lawmaking and will sometimes tell the federal govt to pound sand.