1. Omega being the last letter of the Greek alphabet, that one goes way back. I can't even remembered when I first learned the expression "from alpha to omega..." meaning from beginning to end.
2. Omicron came to me much later. Not having studied classical Greek, I encountered it in math and physics classes where they regularly run through the Greek letters for variables and constants.
3. Metric prefixes is something that was taught to me over and over and now, in the modern computer world, are unavoidable. Who doesn't know a Mega of something is big (10^6 precisely) and a Micro of something is rather small (10^-6 precisely)?
1+2+3 = This morning, Irene was reading about the latest variants in the Corona virus and she exclaims "Did you ever realize it is O-Mega and O-Micron as in Big O and Little O?" Oh my, I did not. So obvious though, once pointed out - how could one have missed it??
(https://www.youtube.com/watch?v=MzlK0OGpIRs)
Turns out it is more like long o sound and short o sound, capital and lower cases are something else in Greek (unless it's the omicron, where there appears to be zero difference):