Where else should I cross post my book?

I wrote my first eBook ( https://gumroad.com/products/fjTSv ) and was very quickly reminded of the fallacy of "build it and they will come". I've taken out Twitter & Quora ads to try and drive traffic to it.

I'm working on porting the book over to Amazon KDP, Apple Books, and Google Play. I'm also working on adding it to the AppSumo platform if all goes well.

It's currently in review at AppSumo and Google Play.

Are there any other locations where I should post my book? Or suggestions on how market it?