For another alternative: I added some monitoring, by using file_fdw. This is a standard pg extension that presents files or program stdout as tables. So I file_fdw'd some files in /proc and some system utilities.
For harder things, read the file as lines instead of fields, then create a view with some regexes to split it in fields:
CREATE FOREIGN TABLE IF NOT EXISTS proc_meminfo(
line text
) SERVER pglog OPTIONS ( filename '/proc/meminfo', header 'false',delimiter '$' );
CREATE OR REPLACE VIEW proc_meminfo_interpreted AS
WITH arr AS (SELECT regexp_split_to_array(line,':| +') a FROM proc_meminfo)
SELECT a[1] as name,a[3] as value FROM arr;
Hardest part is creating semi-legible source code in HN ;-)