I accidentally found my closeted nephew on grindr

So some context before I jump in, I’m (24M) bisexual but also not really out to my family yet (been taking a while to come to terms and figure my own shit out). Anyways, recently I was at my siblings house where my nephew (17M) lives, helping babysit all the kids while their parents are away. Once it got close to midnight and everyone was in their rooms or asleep, I was still up and bored so I opened grindr after scrolling away on other apps for a while. That’s when to my surprise I see the first blank profile say 0 feet away and with some descriptions that matched my nephew (except for the fact he was claiming to be 18). Now I know I can’t be 100% sure since there were no pictures, but believe when I just know based off of what details there were.

I’ve always suspected he was gay based off of his traits and personality in certain ways, I have a decent gaydar even though I’m not even out myself. My dilemma here is that (1) I don’t know if he noticed my account, which is also blank publicly, but my age and descriptions could still give me away (2) I can’t decide if I should acknowledge all of this and talk to him, because I understand being all alone with this kind of secret and (3) he’s lying about his age and I’m concerned for his safety possibly meeting up with who knows what kind of people and how old.

The following morning/ day we acted normal and didn’t acknowledge anything or feel weird so that’s why I’m not sure he knows I know what he’s up to. I do not want to out him by talking to his parents/ my siblings because it is not my conversation to be had. But I also feel guilty now knowing all of this and that when he says he’s going to one place he’s lying and going to hook up with someone. I was never this bold at 17 and didn’t even get grindr until Ike a year ago so I just want to make sure he’s safe in all of this but also to maybe let him know he’s not alone. Plus honestly it’d be kinda nice to know I’m not alone in the family either, cause no one else is lgbt. Basically, my point is that this could maybe make us closer or could ruin our relationship too if I scare him by bringing this up (especially if he didn’t see my acc, but I didn’t see his profile anymore the next morning so maybe he blocked me cause he did notice it was me ? )

I don’t want to make him uncomfortable in any way, and I can’t even be one to talk or judge in any sort because I’m still DL and in the closet too so I can’t even be a leading example for him. If anyone could lend some advice on a good way to possibly handle this or even tell me I should just leave it be, I’d be very appreciative. Since I’m not out I don’t have anyone irl to ask what I should do so I’m asking strangers here.