Elections are swayed by tiny numbers of votes. Power rests with small groups of retired homeowners who bother to show up. And decisions made there have a greater impact on your life than most elements of federal policy.
so much this, young americans are systemically disenfranchised by how local governments are run
If by "routinely disenfranchised" you mean "regularly fail to show up to vote" then I would agree with you. Perhaps with the exception of university students registered at a parental home, I don't see how one could claim young Americans are materially disenfranchised in regards to local elections.
Ironically, we are almost there, but my swimmer is about to graduate and will probably never swim in the pool.
Perhaps this disenfranchisement is more of a regional issue.
Are there restrictions on non US citizens?
Your representatives make decisions about zoning codes and land use policies that are the literal rules for how your city is organized. They can do things like pass tree ordinances that regulate when people can cut down old growth trees, make a bicycle master plan to improve mobility in the city, establish incentive programs for entrepeneurs in targeted industries to boost the local economy, and more.
I am not sure where you live, but I find the opposite is true. Where I live, in Denver, CO, USA, I have found that my city council members and state reps are often responding to emails directly since they have little or no staff.
I have found them to be super receptive and easy to talk to. If you have concerns, and you are polite and thoughtful, your ideas will carry weight with them.
This is a town of around 100K.
The public comment period at city council meetings is not where change happens, sadly. It should be taken more seriously by both officials and the public.
You can and should yay or nay developments of importance locally but some things are on long time tables or resource constrained such that they wouldn't be that great of an idea even if they had broad support in principle.