I'm extremely open, basically anything about me has been said to at least someone and a lot of information on me is publically available. People will tell you to "speak up" if you're struggling but in my experience it never does any good. You'll have people who get worried, people who get hurt, people who get triggered from their own trauma, people who get tired from all the negativity they can't do shit about, people who don't understand, people who give 0 shits, people who invalidate you or react in toxic ways like victim blaming that only make you worse, people who get frusrated, people who get distant, people who use it against you (luckily this hasn't happened to me yet but I've seen it happen), or force you into a hospital that will likely treat you like garbage (luckily this hasn't happened to me), etc.
It's usually pointless. There are some exceptions.
Also most people just.. don't give a shit. They give a shit if your suicidality mildly inconveniences them, and they may call a procedure they were told to (suicide hotlines, hospitals) or just do nothing. But they don't really tend to care no matter how obvious you make it. And some do care, but in an invalidating, toxic way. Like how you can get arrested for attempting suicide in places.
That's not to say there aren't any people who genuinely care. It's just not the norm, and usually they've been through shit themselves. And they often can't do too much. For me mostly my best friend and my mom and dad care, but neither really understand me and have still said things that actively pissed me off. My councelors seem to care a bit but ehm, at the end of the day they are paid to and once I'm not a client anymore they won't care.