The RAM consumption question is hard to answer scientifically. But if you want to reduce your footprint even further you can use Artix to drop systemd and replace it with an init system such as openRC or runit.

You can swap DWM for sway if you want to Wayland proof your desktop without sacrificing that much memory and use foot as your terminal.

In any case your RAM usage will skyrocket if you use any HTML5 web browser (like browsing hexbear).

But really RAM usage on Linux is fine. People say that any unused RAM is wasted RAM and I'd agree. Unless there's a memory leak or anything related to chromium or firefox your RAM usage should remain low. If you really want to push Linux to be even smaller you'd want to look at Puppy-Linux or Damnsmall Linux.