You can do this using match RegEx rules with extra characters to match the start or end of the genre.
The /i version makes the comparison case-insensitive.
Use a ^ to match only at the start of the genre.
e.g.
Genre > match RegEx /i > ^Rock
(https://i.imgur.com/zpgmDV6.png)
This will match "Rock" and "Rock & Roll", but not "Progressive Rock"
Use a $ to match only at the end of the genre.
e.g.
Genre > match RegEx /i > Rock$
(https://i.imgur.com/bm3YJ3e.png)
This will match "Rock" and "Alternative Rock", but not "Rock & Roll"