Is there an update on this?
Kind of but not by me. The chinese manufacturers made this case which is what my one was going to be but my one was going to have the plunger on the back screen and no cover for the front.
https://www.aliexpress.com/item/1005001640988542.html
I bought the original version of this which didnt come attached to a bumper(you were expected to remove the bumper and stick it with the adhesive strip the case came with. But that adhesive was weak and kept on unsticking.
This new design they've made integrated with the bumper seems better but I think they should use magnets instead of a plunger because sometimes it's worrying how much it pulls on the screen before it pops off.
For the moment my case of choice is this one in black, I just take it out when I want to unfold. But it allows the back to be used while the case is on which is what I ultimately wanted. You just tap through the case since there's no hole which is what I wanted and taps work as normal
https://www.aliexpress.com/item/1005001652194534.html
I check aliexpress every couple of days for new designs so if there's one which is the "perfect" case, I'll be sure to post it here on the mate xs forum