$ digikam
GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium.
xkbcommon: ERROR: [XKB-661] Couldn't process include statement for 'us(101_qwerty_dot_dead)'
xkbcommon: ERROR: [XKB-769] Abandoning symbols file "(unnamed map)"
xkbcommon: ERROR: Failed to compile xkb_symbols
xkbcommon: ERROR: [XKB-822] Failed to compile keymap
[76755:76828:0316/213919.334093:FATAL:xkb_keyboard_layout_engine.cc(661)] Keymap file failed to load: us,hu(101_qwerty_dot_dead)
Trace/breakpoint trap      digikam


That's all it can do when I have the setting:
setxkbmap [...] -layout 'us,hu(101_qwerty_dot_dead)' [...]

I figured out that it interprets the layout in a faulty way:

'us(101_qwerty_dot_dead),hu(101_qwerty_dot_dead)'

while it is, according to setxkbmap:

$ setxkbmap -print
xkb_keymap {
        xkb_keycodes  { include "evdev+aliases(qwerty)" };
        xkb_types     { include "complete"      };
        xkb_compat    { include "complete+grp_led(scroll)"      };
        xkb_symbols   { include "pc+us+hu(101_qwerty_dot_dead):2+inet(evdev)+compose(paus)+group(sclk_toggle)+group(shift_caps_toggle)+level3(ralt_switch)+terminate(ctrl_alt_bksp)"    };
        xkb_geometry  { include "pc(pc104)"     };
};

So xkbmap see properly "pc+us+hu(variant)".

I cannot easily hack it since 'us' does not have a useful variant (for example it
works with 'us(intl),hu(101_qwerty_dot_dead)' but us(intl) is not what I'd use).