final update!
around 11AM EDT today, tracker showed biometrics (for the first time), medicals, and eligibility as completed. background still in progress.
application history section on the tracker also showed this update today backdated to 28th March: 'We received the information you sent us. We’ll review it and let you know if we need any other information from you.' (i hadn't sent anything or was asked to).
gckey had no update (i did receive a ghost update on 29th March, one day after my gckey background check was updated to processing).
and then around 1:10PM EDT, I received the RFV request email.
(tracker still shows background in progress. gckey still shows reviewing eligibility, and background processing.)