It seem like what you want is a large version of the Beeminder Watchapp for Pebble (bottom of post), which was in part designed to show the users progress towards a goal on (a smartwatch with) an e-ink display. You should be able to run the emulator on your Raspberry Pi. The watchapp source code is here and it can easily be modified to show any other information from the Beeminder API…
Here are some links where others have done something similar:
- https://www.reddit.com/r/pebble/comments/4k8zkf/i_created_my_first_watchface_and_had_an_extra/
- https://www.reddit.com/r/pebble/comments/3lqtsz/ok_i_have_pebbe_walldesk_clock_now/
- https://www.reddit.com/r/pebble/comments/2xhv2n/pebble_next_announced_is_going_to_be_digital/
- https://www.reddit.com/r/pebble/comments/3kgsn1/going_to_make_a_pebble_wall_clock_i_think/