If they want to give DC residents voting rights they should make it impossible to be a DC resident and instead anyone who lives within DC should vote as part of the state the land was taken from for federal elections.
That solves everyone's problems (well aside from the democrats who are trying to get another 2 seats in the senate).
Local issues should still be decided at the federal level because that's the whole reason it exists, so a state can't take the seat of fed gov hostage as happened in 1783 in philly.
If you don't want DC to be controlled by the fed then it should be swallowed by maryland or virginia. Making a single city a state unto itself doesn't make any sense unless you're specifically trying to make political hay.