I'm using Civi 5.31 on Drupal 7.
I want to enable self-serve check-in / sign in for an Event. Attendees should be able to click a link (and/or scan a QR code) to either RSVP for the Event, and receive a Status of Attended, or, update a previous RSVP with a Status of Registered to Attended.
Only attendees physically present at the meeting, or participating via Zoom, Jitsi etc will be given the link/shown the QR code to scan.
There is an existing self-service capability for participants to Cancel or Transfer a registration, and to set time limits for a 'window' within which to cancel or transfer. Self-serve check in / sign in could work similarly.
I know there are various ways for 'staff' or a meeting organizer to do this for all attendees, but I want to avoid the manual tedium of updating multiple attendees from Registered to Attended by allowing self-serve check-in/sign-ins.