@Garmin have you considered making/including a Velocity Based Training feature for sprint work (or custom running workouts)? I.e. if i make a custom workout where I planned to do maximal intensity sprints (for example 4 x 10m accelerations, 4 x 30m sprints, 3 x 50m sprints and 2 x 100m sprints), it would be beneficial to see the top speed reached (and maybe also time taken to run x meters). If i know my top speed across those distances, I can more accurately get an idea of when I've done too many reps where I'm no longer training for acceleration/speed, but becomes more anaerobic capacity work.
Example: If my top speed over the first rep of 50m is 35km/h and I want to make sure that I keep my reps as close to that as possible, I may use a 10% drop-off value. Thus, if my speed drops below 31.5km/h before the end of my set, I won't do any more reps and will cut the set short.
Consequently, this could also allow people to do speed/sprint-based training more effectively, as they can just do reps until they reach their velocity drop-off value rather than a fixed amount of sets and reps. Utilising such a velocity-based training approach may also be more sensitive to day-day physiological fluctuations (e.g. due to poor sleep, increased stress...) that can affect high-power work (e.g. sprints) to a greater extent than endurance work.
Provided GPS data is accurate enough, I don't see a reason why Garmin do not have the capability to implement this.