Per Kind signer approvals are great for the Pros but I think it's completely unnecessary for regular users. Maybe not even the Pros use per kind approval screens regularly.

Somebody could design a simpler, fully offline EasyAmber app that simply holds the key safely, accepts a one time permission request for each app and then automatically approves everything. The main screen is just a collection of current sessions open.

No, your keys cannot leak in that way. Literally impossible.