Gajim for jabber chat! And OMEMO for privacy (who knows what the admin at mage.party can see?!).
Flatpak for the win:
flatpak install flathub org.gajim.Gajim
Flatpak apps may be containerized with access to each other, that’s how they have permission to operate together. For Gajim that means plugins are installed via flatpak as well, and have some docs at flathub · Wiki · gajim / gajim · GitLab.
[maiki@violet ~]$ flatpak search gajim.plugin
Name Description Application ID Version Branch Remotes
URL Image Preview Pl… Display a preview of links to images …im.Plugin.url_image_preview stable flathub
PGP Plugin XMPP Extension Protocol (XEP) for secure mu… org.gajim.Gajim.Plugin.pgp stable flathub
OpenPGP Plugin Experimental OpenPGP XEP-0373 Implementation ….gajim.Gajim.Plugin.openpgp stable flathub
OMEMO Plugin XMPP Extension Protocol (XEP) for secure mu… org.gajim.Gajim.Plugin.omemo stable flathub
Ayatana Appindicator… Integrate Gajim with the Ayatana AppIndicat… …m.Gajim.Plugin.appindicator stable flathub
Installing OMEMO as a flatpak is so simple! And it just works, too. 
flatpak install flathub org.gajim.Gajim.Plugin.omemo
While I’m at it, I’ll go ahead and install the image previewer, which previews images served to me from the jabber server.
flatpak install flathub org.gajim.Gajim.Plugin.url_image_preview