1.- You have a backup with a series of tables which get inserted WITH a timestamp. Adi-The series of tables may or may not have timestamp
Then I think you cannot do what you want using only built-in PostgreSQL capabilities. Meta data
about when a record was inserted and/or delete is not kept by the system.
I'm not familiar with the capabilities of logical replication so that may provide an answer I am unaware of.
Otherwise the only thing that comes to mind is to stream WAL to an intermediate server and then every so often (once a day) release to the other server all WAL that accumulated during the previous period.
None of \copy, COPY (SQL), or pg_dump will get you what you want - the persisted data doesn't contain the information you desired.
Alternatively, once a week (give or take) you could perform a base backup of the DB. Stream all archive files somewhere and each day perform a "point in time" recovery.