Seeing the chatter here that others were finding links in the app/account to claim but not seeing any such links for myself, I wrote to United on Twitter to make my case for why my spouse and I were eligible for the miles given our overnight delay and then cancellation on 26 June. Whatever tool the Social Media Team has returned a denial so they suggested I submit a formal inquiry through Customer Care, which I just did. For the record, the Social Media Team provided the following as the official qualifications for the 30,000 miles:
Passengers who had flights booked to travel for Saturday, June 24, 2023, through Friday, June 30, 2023, are eligible to receive 30,000 MileagePlus miles if they meet the following criteria: Experienced an overnight delay, OR Their flight was canceled, and they were not rebooked/chose not to travel. ^AF