The error occur when I execute M-x geiser-mit in emacs (which version is emacs-plus@29)
I've tried to (restart 1) as it mentioned.
But it seems just ignore the error.
The error indicate that I have to bound geiser a value.
But where and how?
I've tried M-x geiser RET mit RET, but still the same error.

I tried on two mac, one (macos version: Monterey)succeeded, the other one(macos version:sonoma) failed like you did
screen print on succesfull one:
I compared the two logs
My conclusion:
in compile.scm (cf "emacs") failed, then "geiser-unx.pkd" can not be found to load