alt Hacker NewsBookworm will get updates for another year if I have read the Debian Wiki correctly so perhaps there is no need for immediate action as Bookworm becomes oldstable?
In addition to Mint and AntiX there is also Slackware (I use xfce rather than KDE) but adding software outside the (large) base install is not an 'apt-get thing' process.
Salix Linux, based on Slackware, does have package repositories with a reasonable selection of applications. Salix is based on the stable Slackware 15.0 so has nicely aged packages.
Void Linux also has an xfce4 based live i686 iso you can look at and decide to install from.
I also use xfce, my computer is an Acer Aspire One, limited in ... well everything, I did upgrade the storage to an SSD, but it's still an Atom CPU, so whatever is the lightest is the best.