Distinct steps we can take as voters.
Challenge all voters who are registered to PO Boxes and homeless shelters. Get the lists from your state. Take these names off the lists.
Work in your local counties - you know your own space/community.
Challenge all dead voters registrations. Use the local newspaper obituary records as evidence. File with the county registrar.
Again, you know your own community.
This is probably the easiest. All these people who died during COVID. File challenges now.
Get the paperwork flowing locally.