I'm always bemused by these tales of Scandinavian unisex utopias.
Largely because they're untrue, afaict. (Speaking from Finnish experience.) Nudity, particularly in saunas, is certainly far more common.
But mixed-sex in that situation is rare. It can happen in close families + friends, yes. Basically wouldn't happen in public, or at workplaces. Those would be single-sex.
To suggest that mixed-sex nudity is the norm is false. It might be more common absolutely, yes - due to the increased nudity generally - but still not the norm.
And to suggest that even that more-mixed-nudity situation would be remotely the same as there being NO single-sex facilities is a total nonsequitur. The total elimination of single-sex options is the problem here. Not the existence of mixed-sex options.
The extra nudity at events actually means a bit more thought needs to be applied to sex separation - eg a work event might need to allow for separate female + male sauna time. Men stock up with beer from the beer fridge in the sauna changing room before the women's turn.... (Yes, offices can have a sauna, but I can't imagine a mixed-sex work sauna).