See: https://github.com/EGjoni/Siikr/blob/main/siikr/siikr_db_setup.sql#L942

Since the siikr DB user is specified in the siikr.conf file, it should be reflected in the SQL as well. To fix this, I think it may be worth splitting up the SQL into a static file that has all of the database creation stuff and function definitions, and then a "template" SQL file that uses the environment variables defined in siikr.conf.

So the SQL template file might look something like this:

GRANT ALL ON FUNCTION public.vector_out(public.vector) TO ${pg_user};
GRANT ALL ON FUNCTION public.vector_recv(internal, oid, integer) TO ${pg_user};
-- ...etc

and then doing an envsubst to create this custom file somewhere (and hopefully cleaning it up afterwards)

source "$script_dir/siikr.conf"
template_out="$(mktemp)"
envsubst "$script_dir/siikr/siikr_db_setup_nonstatic.sql" > "$template_out"
psql -U "$pg_user" -d "$siikr_db" -f "$template_out"
rm "$template_out"

Unless there's an easier way to do it.