For some reason your post reminded me of a list I saw quite recently of (surprisingly working) open/free news servers (maybe dotsrc was on it).

I can't seem to remember or find the exact list or page I saw before, but for anyone interested here are a couple of sites with a few of the other servers I remember.

Note: I haven't tested these, some may not work, some may not be deliberately open (perhaps just misconfigured), some may not allow posting, some may require registration, some may carry only a few local groups, etc etc etc.

Also, this post is related to text usage; if any of the following servers carry binary groups it's unlikely they'll have complete files.

    blaine.gmane.org freenews.netfront.net news2.informatik.uni-stuttgart.de
    news-archive.icm.edu.pl news2.neva.ru gandalf.srv.welterde.de

https://freenews.maxbaud.net/free-usenet.htm

And here:

    news.tin.org news.prz.edu.pl gandalf.srv.welterde.de pb1.pair.com lugnet.com 
    ingebrigtsen.no freedommail.novaithelp.com news.alaska-software.com richelieu.ac-versailles.fr 
    news.cadsoft.de news.omnitel.net news.tugraz.at news.mt.net.mk news.man.rzeszow.pl 
    serv3.vsi.ru news.szaf.org pair1.php.net news.sotcom.ru news.mozilla.org x6.develooper.com 
    hq.tin.org news.grc.com iad.wholesalenewsinc.com news.math.ncu.edu.tw bbs.math.ncu.edu.tw 
    news.securecomp.org guest.dogagent.com ddt.demos.su news.dbase.com newsfeed.iif.hu 
    news.iif.hu vm-news.spline.inf.fu-berlin.de news.spline.inf.fu-berlin.de mx.sotcom.ru 

https://www.freeusenetnews.com

There's also https://www.eternal-september.org/ which offers free access to non-binary groups.