Seconding Roxane Gay! I'm planning to do her book Hunger for that square. I read Bad Feminist last year too, and it was really good as well. And if you want to read something suuuuper heavy I read Stamped From the Beginning this year too, which is basically a complete guide to racism in America, from the 15th century and on, which is written by Ibram Kendi, who is African American. But yeah, it took me about two months since it's so comprehensive and heavy.
For mental illness: Julie recommended The Rest of Us Just Live Here to me this year, which was so good. There's also Am I Normal Yet?, though it super triggered me because the main character descended far into OCD hell whereas the former is more dancing around it and the main character recognising it before it goes too far.
The easiest one for indigenous is Sherman Alexie, I think, though I'm planning to try and find something about the Sami, Swedish indigenous people this time.
Disabled main character is HARD. Last year I reread Feed by Mira Grant. I think Kaleidoscope (edited by Alisa Krasnostein and Julia Rios) would qualify too, it's an anthology with diverse YA as a theme, and that ranges from race to disability and sexuality, etc. Not all the stories have all the things in them, obviously, but it should still count.
I have no idea what to do for most of my squares tbh, I'm still thinking. But it's fun to see people using my card, so thanks for that.