I'm with ya, always on the lookout for a purple accented theme as well. I'm really not positive but I always set purple in windows 11 and use assorted tools to darken things, and windows doesn't seem to like purple. Its constantly changing it to something more pinkish as it thinks the purple will be hard to read. Its frustrating. But I wonder if that's the reason its not common in themes?
I dunno just speculation.