Thanks for the exhaustive answer.
So first the answer: no it is not possible at this moment.
The solution you showed works now I know the steps. So what i did wrong:
My mistake was to right-click the CD that I got after a lookup CD and then do a lookup in browser (sending you to the disc without showing the discid and in my case a wrong one hit) or do info, and get only information on the cover image used, nothing more. I would love to see more info at info…
Example group: https://musicbrainz.org/release-group/96eef15a-4926-3482-93a2-749553c5ef1e
Disc at hand: https://musicbrainz.org/release/a81e4130-e2c4-4aec-b2db-583b6508a1a7
that last one has an ID now, but before it did not have one, and only the ‘other one’ https://musicbrainz.org/release/f95fbfc3-c99b-461c-9b18-ca7269fafd7f was shown, as that has the DiscID attached.
And my remaining question is: what is the chance that this discid is only for the EU one, and not for the US one…