Display content from 2 different CMS sets

Hi everyone,
we are struggling here and asking the community help.
we have 2 CMS systems:
i) blog CMS-1
ii) portfolio CMS-2

We want

  1. to display posts from the portfolio (CMS-2) in the CMS-1
  2. two CMSs have tags in them and some tags are equal.

Does anyone have an idea or a hint on how to realize this?
Thank you in advance!
P.

(how to access public share link)