recover a physical standby to a specific point in time.

Okay, let me set this up for you. We have primary with a remote standby. We are currently running at a 4 hour apply lag and am looking to increase it to 12 hours in incremental steps (the old space issue thing). What we would be interested in doing would be using the standby as data recovery as needed and as a full DR standby should we lose our primary site.

What I'm thinking since we're on 19c is to use the ability to take a guaranteed restore point on the standby, cancel the apply, recover the standby to the needed point, open it in read only to recover the needed data and then flashback the standby to the guaranteed restore point and start the apply process with the appropriate lag.