Drop in a GPX file and get a widget URL that contains the whole track — no upload, no account, nothing stored on a server. The file is read in this browser tab and never leaves it; the resulting link is the only copy of the route, so whoever holds the note holds the data.
Detail is how far the drawn line may stray from the recording, in metres — the lever that trades URL length against fidelity. Most of what the first few metres discard is GPS jitter, not hike. Trim ends drops that much track from the start and finish, so a route recorded from your doorstep doesn't publish your doorstep.
Paste that URL into a Mimir block and it renders as the map above. It stays readable forever without this site's help for anything but the basemap tiles — the coordinates are in the link itself.