Reusing the same connection to read uncommited transaction
You can only see uncommitted data modifications withing the transaction that performed them, so your client code would have to use the same transaction for everything. This sounds a lot like you are going to end up with long running transactions, which is a very bad idea in database, particularly in PostgreSQL.
I recommend that you approach this in a different way. Add a column committed to the table that you set to TRUE or FALSE (or something similar). Then you don't have to keep transactions open for a long time, and other transactions that choose to do so can simply SELECT “uncommitted data”.