The picture I linked is of a buckwheat pillow. Had no idea they were a thing before today.
What about silk or bamboo pillow cases?
I've only ever really used cotton pillow cases and cotton stuffed pillows. I recently upgraded to a foam pillow that I'm enjoying.
I have the Purple Harmony pillow. It took some getting used to, but yes, it's worth it. I use a silk pillow case because of my hair: 4C hair is dried out by cotton and people recommend not sleeping on it as a result. My hair has never been longer though, so I think that's true too.
I also got a purple pillow on a friend's recommendation. I'm a really hot sleeper, and a side sleeper, so I need a lot of pillow and it was hard finding both of those things in one pillow for me. It's been great, I like it a lot. The main downsides are it's heavy as shit (the pillow probably weighs like 8kg, it's wild), the weird rubbery texture takes some getting used to, and the little mats they give you that go under the pillow to make it taller get bunched up if you move the pillow too much.
Other than those minor complaints, I've really loved it. It stays very cool, while still being springy and contouring.
I haven't really experimented with other pillowcases, but I have been meaning to, if anyone knows of something nice.
Had to go check then out when you said yours was EIGHT KILOGRAMMES. Crazy pillows.
I haven't ever weighed it so that might be a bit of an overestimate, but not by much lmao, it's ridiculously heavy