On Ubuntu 21.04, this script enables gnome-terminal to show sixel images. (Ref: https://www.kofuk.org/blog/20210803-vte-sixel/, https://twitter.com/man_2_fork/status/1422514528886030337?s=19 )

build_vte_head.sh

#!/usr/bin/env -S bash -e

# REPO='https://gitlab.gnome.org/GNOME/vte.git'
REPO='https://github.com/GNOME/vte.git'
LIBPATH='/usr/local/lib/x86_64-linux-gnu'
LDCONFPATH='/etc/ld.so.conf'

# See Deps:
# https://github.com/GNOME/vte/blob/master/meson.build
# On Ubuntu 21.04, GNOME-Terminal 3.38.1:
pip install meson
sudo apt install build-essential git libfribidi-dev \
                 libgirepository1.0-dev libglib2.0-dev \
                 libgnutls28-dev libpango-1.0-0 libpcre2-8-0 \
                 libpthread-stubs0-dev libsystemd-dev ninja-build \
                 python3-pip valac zlib1g-dev -y
(
    [ -d "./vte/.git" ] || {
        git clone --depth 1 "$REPO" vte
    }
    cd vte
    meson . _build -Dsixel=true && cd _build && ninja
    sudo ninja install
    grep -q "$LIBPATH" "$LDCONFPATH" || {
        sudo sed -i "1iinclude $LIBPATH" "$LDCONFPATH"
        sudo ldconfig
    }
)

echo -n "done! kill all gnome-terminal-server?(n/y): "
read -r i
[ "$i" = "y" ] && killall gnome-terminal-server