@supas Unless they’ve done away with it, which I doubt, it’s there. It’s just not where you’re looking.
For bookmarks, goto the URL
opera://bookmarksand use the drop-down at the bottom left to export bookmarks to an html file. You can then import them into other Chromium-based browsers like Chrome and the new Microsoft Edge. And, you should be able import them into Firefox as well.
Above is from https://forums.opera.com/topic/40531/exporting-bookmarks-and-settings-from-opera-to-other-browsers
Then there’s one from this year, https://browserhow.com/how-to-import-and-export-bookmarks-in-opera-browser/#export-bookmarks-from-opera
So one or both of those should be the answer.