those don't get posted because they don't require any sort of redeeming from the person who wins since it's sent directly to them. However, If you wanted to check who won (even if you didn't win/just for curiosity sake), you could pull up the stream or check unaffiliated TG channels that post them to get the random post numbers and look them up to see who won those. [As in, open the thread, find the post number, and see who made the post.]
But say you wanted to know who won for the forum page winners, where a host selects them, then you could ask the host that was assigned to the page you wanted to know the winner of (usually if you believe your post was on that page, just double check before asking though since post numbers will change prior to the thread being locked). But, say you don't think you won and you just wanted to know who won (purely out of curiosity, and not because you had a chance of winning and wanted to confirm that you didn't win since nothing was sent to you), you'd have to ask each host who was assigned each page (using the recorded stream) and then ask each one of them to tell you who they chose.
Otherwise, as you might be able to see, since the winners for the page numbers is up to each host who was assigned to it and who they pick is done by so many different people, there's a good chance that getting all the different hosts to report back for each page who they chose to win is kind of a lot of extra work and might be why they don't post it but otherwise, and I'd guess the more likely reason is because, usually the only one who'd care to know something like that is someone who thinks they had a chance of winning after hearing their page get called but didn't receive anything and, so in denial of not being picked the winner, they wanted to see who was chosen instead of them just to confirm for themselves that it was in fact not them who had won, then it just seems like a more simple answer for them, or those who think like them, would be for them to realize, if it hasn't been sent to them by the end of the day, they can be sure it wasn't them..
Basically, ~TLDR~ unless you just want to know for curiosity's sake, then chances are you're just looking to make sure you didn't win because the reality is, if you had won, you would've received it the same day. And, if you wanted to know for curiosity's sake, then you'd have to put in some work to find out.
If it's any consolation, if you think your page was picked, double check your post to see if it's still on the page you thought it was on and if it was and it was a page that was picked, then if you really want to know who you lost to then you could ask the host who was assigned to pick a winner from that page, pulled from the stream of course (or TG channel aforementioned).