I'm aware that MX works on a lot of excellent GUI tools that are shipped with it. Which is great, but perhaps necessary; because they ship a systemd-less distro. Which, in the end, might cause more work than it should. (I'm aware this is in part caused by software just assuming that systemd is installed by default.) And while I think it's a noble endeavour to maintain a relatively easy systemd-less distro, I don't think it's enough to justify a recommendation to a relatively new Linux user. Would you mind sharing your thoughts on this?
This is the answer. Current stable Debian already has the latest release of Xfce (4.18); and for recent gui apps there's flatpak.
For packages like syncthing you can enable official apt repos to get the latest versions.
Other packages for which the latest versions are desirable though the flatpak versions get a bit too finicky (like vim & emacs), you can compile from source. It's not hard, even for a newbie.