macOS unable to open any non-Apple application

A temporary work around that helped me was to use

  sudo route add -net 17.253.17.207 255.255.255.255 -blackhole;
  sudo route add -net 17.253.17.202 255.255.255.255 -blackhole;

based on

  dig +short ocsp.apple.com |grep -E ^[1-9]
  17.253.17.207
  17.253.17.202

That shortens the delay. Others here found adding ocsp.apple.com to /etc/hosts using a private address also helps. Whichever is easiest for you. To remove:

  sudo route delete -net 17.253.17.207 255.255.255.255;
  sudo route delete -net 17.253.17.202 255.255.255.255;

or reboot.