Same thread, I just think these are two somewhat separate changes. One is just in the walsender and allows return to command mode during waiting for WAL. The other is more intrusive into the reorder buffer etc and allows aborting decoding during commit processing. So two separate patches make sense here IMO, one on top of the other.
About the second part of the patch. What the reason decode and send whole transaction? Why we can't process logical decoding via WalSndLoop LSN by LSN as it work in physycal replication? For example if transaction contains in more them one LSN, first we decode and send "begin", "part data from current LSN" and then returns to WalSndLoop on the next iteration we send "another part data", "commit". I don't research in this way, because I think it will be big changes in comparison callback that stop sending.
