Wow, you weren't kidding, it's a much clearer picture. And it looks really nice! Which one is more likely to be the final design? The flat one or mister bumpybottom?
Also, since it's gonna be asked sooner or later it might as well be me: Is there a plan for multiple keyboard layouts (or stickers)?

If this works nicely with the jolla tablet (you mentioned minimal case modifications for keyboard attachment?), sign me up – even in case I won't be able to get one of your tablets! I've had some BT keyboards that wouldn't work (not even discoverable) with SFOS but worked perfectly with android. Make sure to test the planned chips really early to save yourself some stress and money.