Linux
You first have to install rustup. You can find the up-to-date instructions on rustup.rs.
Then install GTK 4, Libadwaita, Meson, and the build essentials. To do this, execute the command belonging to the distribution you are using.
Fedora and derivatives:
sudo dnf install gtk4-devel libadwaita-devel meson desktop-file-utils gcc glib-compile-resources gtk4-update-icon-cache update-desktop-database
Debian and derivatives:
sudo apt install libgtk-4-dev libadwaita-1-dev meson desktop-file-utils gcc gtk-update-icon-cache
Arch and derivatives:
sudo pacman -S gtk4 libadwaita meson desktop-file-utils gcc