This works for cases where just being a member gets a lower price, but at least some stores have digital coupons that need to be added to my account. This would not work with a generic card. It is definitely a good tip for stores where it does work though.

Grocery store rewards programs. I know they are designed to link purchases to me, but the financial savings is worth the loss of privacy for me.

While still not as seamless as on Windows, WiVRn works great for VR on Linux in my experience.

Thunder and Voyager are my favorites on Android, but Mlem on iOS is my overall favorite.

Never. I have latex foam pillows that are a solid block, so there is nothing to fluff. It took me a while to get used to how firm they are, but I absolutely love them now.

There is Synctrain and Möbius Sync. They are not perfect due to iOS restrictions on apps running in the background, but they work well enough as long as I occasionally open them to make sure they sync.