@Metal-Brain
You can't assign a velocity because of the uncertainty principle. You can peg the velocity but at the expense of pegging the location or Vice Versa but not both at the same time. There is only a probability of a velocity and a probability of location.
An electron has mass so it can't even go at c, only photons can do that, electrons get very close depending how much acceleration voltage you goose it with (there are now silicon chip designs that can do that using IR laser light to accel electrons and they are working on a design that will accelerate electrons to one MILLION volts of accel, which is 0.94c in a silicon chip one inch long.
Implications for research and cancer therapy.
https://phys.org/news/2020-01-particle-chip.html.
The ion implanters I am expert in has max 200,000 volts of acceleration and that using a series of voltage rings totaling about 2 feet long so when the full chip is built, it will shoot electrons 5 times higher voltage in 1/24th the length.
But ion implanters, by name don't usually accelerate electrons, instead we go for the big three in semiconductor manufacturing, making pure silicon, an good insulator, into a decent conductor, hence, semiconductor and the ion implanter accelerates the big three, either phosphorous, arsenic or boron (all three are electron donors or receptors) as dopants to the silicon. Maybe TMI, I'll stop there. It would be a big jump to take the full one megavolt chip to accept ions though.
For now we would LOVE to get one MEV of accel in one inch space even if it is only electrons.
It might mean electron microscopes the size of a hotel room refrig rather than a unit the size of a car as one example.