Current XFCE setup

Ah that's great, I'm literally setting up my own XFCE today after a couple of adventures trying out other potential interfaces and ripping out all the traces of the original KDE Plasma that I had before on my Arch setup. That took quite a bit of work and now I have to re-theme everything, including SDDM!

I am absolutely stealing a few things from your config, like the themes and icons.

I like this overall setup for Ultra-Wide monitors. The icon set is Kora-Grey (part of the whole Kora icon pack on gnome-look). The overall theme is Material-Black-Colors (using the Pistachio-BE option here), also on gnome-look. To do the Date - Time display they way I have, I put the clock widget on twice. Once showing only the date, the other showing only the time. Clicking the date brings up Thunderbird open to the Calendar tab. Clicking the time open Thunderbird on the Email tab. To make the panels rounded, I did add a small .css file in the gtk-3 folder. Can show you what I did if you're interested.
I should have mentioned, the background image is from the finale of Loki. In Norse mythology, it's the Yggdrasil tree.

How'd you get rounded edges on those panels?

I added a little .css file " .config/gtk-3.0/gtk.css" copied below. (there's actually a couple approaches I took, the one I'm using here is not commented out).

/* Two different approaches given below
   both valid but with slightly different
   behaviour
*/

/* This first approach aggressively radiuses
   everything, even items within the panels
   themselves.
*/

/*.xfce4-panel {
   border-bottom-left-radius: 16px;
   border-bottom-right-radius: 16px;
   border-top-left-radius: 16px;
   border-top-right-radius: 16px;
} */

/* This approach is not as aggresive as above.
   Will need to add some transparent seperators
   on either end for the radius to show.
   (16 px for full radius at my current settings)
*/

.xfce4-panel#XfcePanelWindow {
   border-radius: 16px;
}
@import 'colors.css';

For some reason, the formatting is not being preserved here in my cut-and-pasted script. If you can't untangle it, let me know.

I feel XFCE is under-rated. It has the reputation for being "dated", but I find it pretty flexible.