Flatter Linux is a small Alpine Linux based distro that runs Flatter window manager.
Latest iso image can be downloaded from here and tried with qemu.
sha256 0be377659142c73248fc51db1092b56b8ca09251e7029ecc006eba7bd6a71993 alpine-flatter-edge-x86_64.iso
Image comes with Firefox and Chromium browsers pre-installed.