I’ve installed it using the source files. From the notes, the steps I’ve followed are:
sudo apt install -y libgtk-3-dev libconfig-dev libfftw3-dev libexiv2-dev libopencv-dev libraw-dev libffms2-dev libheif-dev libcurl4-gnutls-dev gnuplot cmake libgsl-dev ninja-build libcurl4-openssl-dev sudo pip3 install meson==0.54.2 git clone https://gitlab.com/free-astro/siril.git cd siril git submodule sync --recursive git submodule update --init --recursive meson --buildtype release _build ninja -C _build sudo ninja -C _build install