(to be clear I only skimmed the end of this thread and did not look at
all the previous messages)
I took a quick look at the first patch (about deparsing table ddl) and
it seems like this would also be very useful for a SHOW CREATE TABLE,
like command. Which was suggested in this thread:
https://www.postgresql.org/message-id/flat/CAFEN2wxsDSSuOvrU03CE33ZphVLqtyh9viPp6huODCDx2UQkYA%40mail.gmail.com
On that thread I sent a patch with Citus its CREATE TABLE deparsing as
starting point. It looks like this thread went quite a different route
with some JSON intermediary representation. Still it might be useful
to look at the patch with Citus its logic for some inspiration/copying
things. I re-attached that patch here for ease of finding it.