There are specific limits on the size and functionality of sunglasses at sanctioned track and field events.

Some events don't even allow the use of Garmin watches (by elite runners) because they can be used for pacing.

Very much a non-elite runner here, but yeah, "run vs my previous best pace" is a standard mode and seeing "you are 12 seconds ahead and will finish with a time of xx:yy" is very, very motivating.

Every once counts. Also, it would be a pain to keep on while running.

Are there any ultramarathon runners that wear glasses while they run?

It’s very common to wear sunglasses in an ultramarathon. Runners usually also wear a vest to carry their water, food, safety gear, headlamp, etc.

Different sport altogether, it’s more the endurance so the pace is generally lower. Also you usually won’t have much support along the way so carrying water & food is pretty essential.