Generate data delta between two databases PostgreSQL
The traditional mechanism if you can


Dump the tables at point-in-time into a CSV (\COPY with ORDER BY)
Modify the tables, or wait for modiications
Dump the tables again at a point-in-time (\COPY with ORDER BY)
Diff the CSVs
Thennn


If the rows are not present in the second versions, write a DELETE (or batch for a larger delete)
Otherwise write a INSERT ON CONFLICT .. DO UPDATE (or batch for a larger INSERT)



This handles INSERTS, UPDATES and DELETES and only requires you to check for the presence of the surrogate key. If you don't have a surrogate key, things obviously get a lot more complex. And, even more complex if you have no UNIQUE keys at all.

Alternatively, dump the table as a 50gB CSV as an .xz (or other compressed format) and just be done with it. Probably compresses to a few GB, in a few hours.