We post sys admin / "DevOps" roles on https://www.wfh.io -- but to be honest, the # of these we get (or see online) pale in comparison to development roles.
i look at those boards regularly, some jobs are US-only but not all. on https://www.wfh.io, since march we've had 19% of jobs posted that are open to those in a particular country only.
Have a look and see if there are any Regus office buildings in your town/city. They have an inexpensive membership card that lets you make use of their business lounges. The Regus building I tried wasn't amazing but I would imagine they're all different so may be worth looking at?
Looks to me like these companies happen to use the same service to post their jobs. Not that the comment is advertising a JobBoard or Recruiting service.
Would it be better for each company to post an individual comment with the link to their JobPost instead?
--Matt @ WFH.io