I'm using "Bitstream Vera Sans Mono" as fixed font, and in all other cases "Liberation Sans"; Tried a lot over many years, but any other I've tested so far didn't last long… IBMs mentioned x11-fonts/plex-ttf (hey, package/port - no need for the website) was again such a nice try, but… (Same for the X11 terminal - I always switch back to the classic xterm.)
Icons: I've just installed the ones that my packages are depending on - extended by themes and icons an installed program like Claws Mail offers. As Xfe is my file manager (that's where I mainly see icons - and Xfe brings its own ones) choosing something special is nothing I would see anywhere. But anyway, icons are pointing to the GNOME-Brave ones since years.
Mouse cursor is the "cursor-jimmac-theme" package.
To get themes consistent I'm using "gtk2" as QT theme

The best tools to set up QT (& GTK) on a machine not running any of those desktops is IMO running "lxqt-config-appearance" (from package lxqt-config) and/or "qt5ct".
I've installed some GTK themes that are not available as package, so f.e. the "Stylish-Gtk-Theme" I'm using at the moment (
https://github.com/vinceliuice/stylish-gtk-theme - and from that the "Azul" colors).