Qnx. Although they discontinued it as a desktop os. The ui was nice, but no doubt had maintenance overhead. Minix 3. The rise of platforms like Raspberry Pi ar

Qnx. Although they discontinued it as a desktop os. The ui was nice, but no doubt had maintenance overhead. Minix 3. The rise of platforms like Raspberry Pi are good for alt-os projects because they give a well-fenced compatibility target.