Many such usecases can be achieved by setting a non-personalized cookie, for which you need neither consent nor a popup. You can put a cookie like "has_visited=yes" or "ABtest=B".

If you want to track unique users, well, you're not supposed to unless the users opt in (not avoid opting out!), and you have to accept that at least a part won't - the society and law has decided such desires are not legitimate unless the data subjects themselves want that.