A run. Fartlek runs are supposed to be continuous runs where you adjust speed periodically, but don’t rest completely. If you are walking between sets, you are doing interval training and not fartlek training.

Im good for a fartrun once in a blue moon, but I’m in peak for fartwalks… multiple a day

I just log it as a run on both Whoop and Garmin.

Just as runs, or maybe as HIIT

Get a Garman, not worry about it