Digitigrade legs might seem a little tricky but they're are actually easy to set up and animate. Here's a quick drawover I made on your screencap to show the basic setup...
The key is to set the upper leg bones (i.e., thigh,) to Ignored By IK. With the Manipulate Bones tool, this allows you to use IK up to the knee joint, which works for most of your leg posing. After you've posed the leg from the knee down, press Alt and use Manipulate Bone to pose the LegUp bone. Here's an example of this setup in action...
I've used this setup to animate cats, dogs, dinosaurs and, yup, ponies! You can see how it's used in a T-Rex rig here:
https://vimeo.com/364548450#t=106
Scrub to 01:46 to see how it's used in the Moho workspace.
If you don't enable Ignored By IK for the LegUp bones, the digitigrade rig will still work but it can be a pain in the butt to animate with. Trust me, it's much faster/easier to animate the lower part and upper part separately.
Hope this helps.
Edit: If forgot to mention that you'll want to enable Independent Angle for the toe bones. This helps keep the feet appear 'locked' to the ground, and you can animate the rotation as needed.