Oh. 
You mean, you do not want a text-based Master Password (at least most of the time). I understand now.
I had never heard of people using password managers, but finding it hard to use the Master Password. I see your point of mimicking what mobile does.
Yup, definitely impossible currently. Fingerprint would be neat; a lot of laptops come with them now.
Perhaps a duplicate of this feature request: Fingerprint Support (All Platforms) - To do not re-prompt the master password all the time