After installing a base gentoo OS (no gui)
install evilvm and kodi (or use upstream kodi)

If using upstream kodi, create the file: /etc/portage/sets/kodi and populate with: (adjust accordingly)

app-eselect/eselect-java
dev-java/java-config
dev-java/openjdk-bin
dev-lang/swig
dev-libs/crossguid
dev-libs/flatbuffers
dev-libs/libcdio
dev-libs/libfmt
dev-libs/libfstrcmp
dev-libs/libinput
dev-libs/libtomcrypt
dev-libs/libtommath
dev-libs/rapidjson
dev-libs/spdlog
dev-libs/tinyxml
dev-python/cffi
dev-python/olefile
dev-python/pillow
dev-python/pycparser
dev-python/pycryptodome
dev-python/xkbcommon
dev-vcs/git
media-fonts/roboto
media-libs/intel-hybrid-codec-driver
media-libs/libass
media-libs/libdisplay-info
media-libs/libdisplay-info
media-libs/libdvdcss
media-libs/libdvdnav
media-libs/libdvdread
media-libs/libva-intel-driver
media-libs/libva-intel-media-driver
media-libs/taglib
media-sound/pulseaudio
net-fs/nfs-utils
net-fs/samba
net-libs/libmicrohttpd
sci-libs/kissfft
sys-apps/baselayout-java
sys-devel/clang
=llvm-core/clang-17.0.6
=llvm-core/llvm-17.0.6
x11-wm/evilwm

install the deps with: emerge -quUND @kodi

Ensure you have all the correct use flags defined in /etc/portage/package.use/package.use

Create the file: /usr/lib/systemd/system/kodi.service and populate with:

[Unit]
Description = Starts instance of Kodi
After = systemd-user-sessions.service network.target sound.target startx.service

[Service]
User = kodi
Group = kodi
PAMName=login
Type = simple
ExecStart = sh /usr/bin/kodi-standalone2 -- :0 -nolisten tcp
Restart = on-abort

[Install]
WantedBy = multi-user.target

Then create the file: /usr/lib/systemd/system/startx.service and populate with:

[Unit]
Description=StartX service

[Service]
User = kodi
Group = kodi
PAMName=login
Type = simple
ExecStart=/usr/bin/startx :0 /usr/bin/evilwm

[Install]
WantedBy=multi-user.target

Only enable the kodi server: systemctld enable kodi

If you have Intel GFX, create the file: /etc/X11/xorg.conf.d/20-intel.conf and populate with: (adjust accordingly)

Section "Module"
Load "glx"
EndSection

Section "Device"
Identifier "Card0"
Driver "modesetting"
#BusID "PCI:0:2:0"
Option "TripleBuffer" "false"
Option "TearFree" "true"
Option "SwapbuffersWait" "true"
Option "AccelMethod" "glamor"
Option "DRI" "iris"
EndSection

Section "dri"
Mode 0666
EndSection

#Breaks Gnome when set to false, but breaks kodi if enabled
Section "Extensions"
Option "Composite" "False"
EndSection

Create the kodi user and assign to the following groups:

useradd -G tty,audio,video,render,pipewire kodi

If everything went to plan, executing: systemctl start kodi should fire up X and land you at kodi.