The media are always going to focus on what sells. Maybe mental health issues are not as interesting to the general public as sleazy gossip, accusations of racism within the royal family, etc.
If Meghan is interested in focusing public awareness about mental health issues, she is in a good position to start a foundation, or give her support to the ones that already exist. So is Oprah, for that matter.
But since her problem was apparently being "permitted" to get mental health help when she desperately needed it (and feeling suicidal is pretty desperate), that is an ugly stain on "the firm" or whatever the name is for the institutional protection of the appearance of the royal family. Maybe it's time to let go of Queen Victoria, already?