FWIW, I use Gaia GPS both for planning (website) and in the field. Caltopo is great for at home, and I believe it also has an app now, so it can be used in the field as well. Gaia Premium has a terrific amount of layers that you can use (sat, snow level, shaded relief, cell service, etc, etc.I'd love to learn more about off-trail GPS navigation
Gaia also uses OpenStreetMap for the base map information, which you and I can make better by making changes to it (such as, a road/trail/structure doesn't appear on the map we can add it).
It does have some old maps that you can bring in, but it doesn't have many. I know there is a website out there with historical maps (suggested by Adam Schneider), but now I can't think of it, maybe someone else can chime in.