Found a nice little workaround… for now…
Its a VNC port remote for your iphone - designed so you could use an iphone/ipad as a remote keyboard/tablet.
Has a screen dedicated to Fkeys and a normal keyboard.
I have an old iPhone case/cover Ive stuck an adhesive GoPro mount on the back of - got a kEdge gopro handlebar mount… and hey presto! Music and Zwift controls sorted!