Ines 100% this. There is nothing wrong with nudity in places where nudity is expected (and if you prefer nudity to be limited to same-sex situations, most places have separate changing/washing areas). Getting clean in the shower is not a form of sexual activity, so there is nothing wrong with doing it in front of minors and/or strangers, especially if that is the norm for places like this (and pool locker rooms frequently expect you to take of your underwear before putting on your swimwear, and in many places also expect you to shower naked).
Exposure play, i.e. doing it because it feels sexy to be seen, is different. Though the situation is the same, i.e. you are naked in front of a bunch of other people in a situation where it is perfectly acceptable to be naked in front of those people, the person's motivations are different. If they are deliberately trying to be seen for sexual pleasure, that means that they are deriving sexual pleasure from other people who never agreed to provide sexual pleasure to them. That is not something that you should do with strangers, and if there are minors in the crowd, even worse.
Now, how does a chastity device factor into this. If you use it as a sex toy, as Kaja and her boyfriend do, then it just exacerbates this. If you just had not had an opportunity to take it off, it is a mixed bag, might be a good idea to try hiding it. If you are deliberately going out in the device to be seen in it though, that is bad behavior.
If on the other hand you are using it as part of a 24/7 lifestyle (ignoring the distinction between power exchange with a partner versus using it as an aid to live a life free of masturbation and/or adultery for now), I feel you can be a bit more daring and wear it matter-of-fact-ly, but keep in mind that for strangers, it would still be indistinguishable from a sex toy, so I would still say do not draw attention to it; drawing strangers' attention to those devices is at least as bad as drawing it to your genitalia.
