Can you please share some ideas and scenarios how we can do the PITR in case of disaster.
It depends on what you mean by "disaster". Usually I think that would mean your server (or entire data center) was destroyed. In this case, you would want to restore to the latest time available. I would say that this is not PITR at all, that is just regular recovery.
If someone truncated a table 3 weeks ago, and you didn't realize it until today, that is a scenario for PITR. Are you using "disaster" to cover this scenario?