Sorry for the delay - we have released one more patch along with the required changes you suggested for this to be fully ready for packaging. See below.
The extension packaging seems almost perfect. The only change I had to do to get it pass the testsuite on PG 10 was to make it actually load pglogical in debian/tests/installcheck:
(The needed pglogical packages have not yet been released on apt.pg.o, but there's prereleases in the *-pgdg-testing distributions there.)
For building the packages on apt.postgresql.org, we'd need a place to actually pull the source (package) from. Ideally, you would just add the Debian directory to git, either to master, or in a separate debian branch only. For the tarball, make a release on github (pushing a tag with a sensible name is enough), and add a debian/watch file, e.g.:
That way our build machinery can automatically grab the .tar.gz from github using "uscan" (and also notify about new releases being made).
I like it if the apt.pg.o packages are also uploaded to Debian. Would you be ok if I uploaded the package there? (With you being listed as Maintainer in debian/control?) Christoph