Elsewhere on the forums, @Yiannis128 suggested the following using the Friction value on Calc Velocity. It’s a lot more elegant than my solution, though still a bit hacky. Any suggested improvements, or new approaches welcomed!
Of course, it can also be used on Tick. In this instance, I just set the friction statically, so the character will slam to a stop awkwardly:
For testing purposes, here’s how to measure forward velocity, sideways and upwards drift (also velocity):
None of the above solutions completely eliminates the drift, but @Yiannis128 solution literally makes it 10 times better, and it’s not as finicky as my suggestions.