I have never heard the term Gigaohms used with resistors. Is this a
valid term? With computer hard drives, if a drive is 1000 megabytes,
it's called one gigabyte.

Using some resistor color code software I have, it does not use that
term. For example, brown black gray says 1000M. or red red white is
listed as 22,000M

In real life I have never used any resistor with that high of a
capacity, I dont even know if they are made, but would 1G or 22G be
valid for the examples above?