You could probably do Farmer's Walks or DB Swings in a HIIT format if you used a heavy enough weight to where you were struggling to last 15 seconds (but still using good form). They appear moderate intensity because most people tend to do longer duration farmer's walks and lighter DB swings. It's all about intensity.
I personally wouldn't attempt it with barbell complexes. Nothing wrong with a complex, I just wouldn't format it HIIT style.
There are definitely alternatives to traditional sprints, the key to keep in mind is picking an exercise/activity that you can safely do with High Intensity for 10 to 15 seconds.
James 1:16-17 ESV
Do not be deceived, my beloved brothers. Every good gift and every perfect gift is from above, coming down from the Father of lights
With God's help...Mens sana in corpore sano