Some minor things I bought that have made a difference:

This is more "all cars" but I've really enjoyed having a telescoping window wiper for the windshield - much less putting your shoulders into it.

Also door handle inserts have been great for trips where you want to stash some stuff to be easily accessible - I usually throw my key fob and wallet in the door so I can grab them quickly when I get out without having to fumble around for them or take up space by the drink holders. In a similar vein I got one for the center console as well but I don't use it as much - I just use it to keep the wires from my electronics (LED footwell accent lighting, dashcam, extra USB-c charger for guests - none of these are specific to the CX-30 but still great to have) plugged into the console USB hub. I like to keep my electronics plugged in directly to the USB because the cigarette lighter will keep them running when the car is off, draining the battery.

I also bought this but honestly haven't had a chance to try it out in earnest yet: inflatable car mattress - you can individually inflate portions of it depending on how much space you wanna take up. I like that I can fold it halfway if it's just me driving somewhere that needs a way to car camp without much effort, or fill the whole back seat with it for my partner and I. It does have an inflatable "bridge" for the space between the front seats (pushed all the way up) but the footwells are pretty tall in this car so it's a little weird to get it right.