Curiously, after I logged in via vnc (pinentry did pop up in that session) then killed vnc, pinentry on ssh started working again. I expect this will stop once I restart the regular graphic session.
Meow! -- u-boot problems can be solved with the help of your old SCSI manuals, the parts that deal with goat termination. You need a black-handled knife, and an appropriate set of candles (number and color matters). Or was it a silver-handled knife? Crap, need to look that up.