Going "bare metal" is probably not what you want to do since you want to display graphics.
The 30 second boot time is mainly due to running a "Desktop" distribution with all of the associated daemons and support stuff.
One approach you may want to look at is to use the linux kernel and SDL but none of the normal desktop stuff. After the linux kernel boots, it executes a program called /sbin/init to bring up the rest of the system. It is a normal C program running as root. You can replace it with another program.
This program could then use SDL with a widgit library to do what you want. Google for "SDL widget",
for an example library: http://members.chello.nl/w.boeke/SDL-widgets/
I have used a similar approach for years to do things like this. One other thing, you may want to use
static libraries, so you don't have to worry about using all of the dynamic loading of shared libraries.
EDIT: I forgot to mention that you may want to use C and not an interpretive language like python. It probably can be done, but in my opinion, the further you get from a statically linked C program the
more overhead and support headaches are introduced.
Hope this helps