Wildcard

Yes you could search for *.?g?

The * replaces all alphanumeric characters from the asterisk to the next specified character.
The ? replaces a single alphanumeric character.


More complex but also more convenient:
To have that result in a file go to the command editor:
In Windows press the windows key and enter cmd <Enter> in the field at the bottom of the start window.

A little black window with a blinking cursor opens. Enter the drive designator of the drive you would like to search. Example: H: <Enter> The colon is important.
You will see that the drive designator is now the first character of the new line.
Then enter the command dir "*.?g?">BIAB.txt /s <Enter>

("dir" lists the directory entries, the search string specifies what, followed by a redirection command ">" and a file name without blanks. The "/s" advises the computer to search all subdirectories.)

The computer will work and after a little while it will issue a new line with the drive designator as the first character.
It has written a file with all the file names that match your command sorted under the different directories it has found.

Since it is a text file you can edit this thing with any word processor.

Desktop; i7-2600k, 8 GB mem., Win 10 Pro, BIAB 2017; RB 2017 - latest build
Laptop: i5-2410M, 4 GB mem, Win 10 Pro, BIAB 2017; RB 2017 - latest build