@matstage The Opera flatpak is at https://flathub.org/apps/com.opera.Opera. Also see https://github.com/flathub/com.opera.Opera/. It is not maintained by Opera, but the maintainer tries to keep it up to date and tries to address issues when you file them. Consider it the official, unofficial Opera flatpak. Opera employees reference it.
I see there's https://www.appimagehub.com/p/2194902 for appimage, but it looks unofficial too and doesn't seem to be up to date.
The Opera snap package is at https://snapcraft.io/opera. That one is maintained by Opera. I don't think Opera has the resources and desire to maintain other package formats.
There's a docker image of Opera at https://hub.docker.com/r/linuxserver/opera. Looks like it's kept up to date, but not official as far as I can tell.