I feel you on that. I do think you have a lot of potential to win the SEO game with this plugin, and I may have just found a lead for you.
When I searched "dark mode wordpress" I got this WPBeginner article:
Want to add dark mode to your WordPress admin area? Follow this quick and easy guide on how to add dark mode to your WordPress admin dashboard.
www.wpbeginner.com
In their tutorial they recommend this "dark mode" plugin:
Quickly edit content in WordPress by getting an immersive, peaceful and natural writing experience with the coolest editor.
wordpress.org
...which, according to the most recent reviews, the authors just pulled a fake-out on their users and hijacked the plugin to be something else. So, WPBeginner's article is technically outdated, and as an authority—they hate to be out of date. Your move here is to contact them, fill them in on this situation and request they change the links out with a link to your Dark Mode 2 plugin.
Maybe get an affiliate program setup too. It's hard to get promotion for premium products from large WP outlets and you'll need everything you can to convince these guys.
Next, and here's where you can go bold—WP Tavern recently posted a series of articles about a similar controversy where another company acquired a popular plugin and did the same kind of fake-out on their users. You have an opportunity here to ride that wave of controversy—which got a lot of attention from the WP Tavern readers—and bring this story to their attention. Submit it as a tip and mention that you have your own Dark Mode plugin and any link back to your plugin would really help you as an independent plugin developer.
Strike while it's hot my friend.
😎
