Display screen or portion thereof with transitional keyboard graphical user interface

FIG. 1 is a front view of a first image of a first embodiment of a display screen or portion thereof with transitional keyboard graphical user interface showing my new design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is an enlarged view of indicated portions (annotated as number 3 ) of FIG. 1 ;

FIG. 4 is an enlarged view of indicated portions (annotated as number 4 ) of FIG. 1 ;

FIG. 5 is an enlarged view of indicated portions (annotated as number 5 ) of FIG. 2 ; and,

FIG. 6 is an enlarged view of indicated portions (annotated as number 6 ) of FIG. 2 .

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1 through 2 . The process or period in which one image transitions to another image forms no part of the claimed design. The outermost dot-dot-dash broken line showing of a display screen or portion thereof, as well as the broken line showing of elements of the graphical user interface, illustrate portions of the article and do not form part of the claimed design. The dot-dash broken lines of FIGS. 1 and 2 illustrate the boundaries of the portions of the design from which FIGS. 3-6 have been taken and enlarged.