Opera One lacks of any multi-profile support
Opera does have a manual way of having multple profiles. See https://www.reddit.com/r/operabrowser/wiki/opera/new_profile/#wiki_create_multiple_profiles_for_opera for more info.
and for some reason Workspaces don't separate browser sessions
Correct. That's kind of normal for workspaces to just be a visual separation of tabs. It's just that because browsers like Arc and Zen are more advanced in that area and support assigning profiles to workspaces, users have seen how awesome that can be. You're not the first to wish for Opera to have something like that to. Opera had workspaces first and them having separate sessions wasn't a thing.
