Modern watches have all sorts of features besides time. Pulse, heart rate, pace you're walking etc.
This indicator feature would display your total speed through the cosmos by adding together (or subtracting as necessary) various velocities: Earth's rotation, Earth's orbit around the Sun, the solar
system's orbit around the galactic center, and the motion of the galaxy itself through the larger universe. The speed on the watch would fluctuate depending on your location, time of day, and the direction these different velocities are aligned or opposed.
Tapping on different areas of the watch reveals a breakdown of:
Earth’s Rotation Speed:
"You’re rotating at X mph relative to Earth’s axis."
Earth’s Orbital Speed:
"You’re orbiting the Sun at 67,000 mph."
Solar System Speed:
"Our solar system is orbiting the Milky Way at 514,000 mph."
Galactic Drift:
"The Milky Way is moving through the universe at 1.3 million mph."
A timeline at the bottom could allow users to scroll forward or backward to view how their speed will change during the day, month, or year as orbital alignments shift.
I'd probably set it just for solar system / Earth orbit / Earth rotation net speed calculation.
Why? Dunno. Might give you a sense of perspective or something.