I'm not sure what "lakh chauraasee" means to be exact.
IN some gurbani shabads, such as by Bhagat Trilochan jee "aree baaee gobind naam math beesrai" - this shabad gives many life forms. Prostitute, ghost, pig, snake, etc.
However it has not said "african snake" or "mid-western pig" it has just said the name of the animal.
I am guessing that each animal has some gun-augun (virtues and vices) and based on these each is a joon or "life-form" and there are 8.4 million of those.
It could be that pigs are all one life form, doesn't matter which type of pig. Lions are all one life form, doesn't matter which types of lion. However maybe when you get to humans this changes. You could be a ghost human, or a prostitute human, etc. Because humans are more definable as far as "gun-avgun." Therefore this could be the method of definition of the 8.4 million life forms.
I do not think Guru Sahib was giving a ball-park figure or an uneducated guess, Guru Sahib gave an exact number in Guru Sahib's infinite wisdom.
Gurbani is definately limitless and infinite and therefore Gurbani must address the life forms beyond this earth.
I don't know if the 8.4 million life forms are from this earth or also include aliens.
However Gurbani has said that God has created all creatures, and that there are many planets and many universes and many khands. I think more gurbani research would yeild a more satisfying understanding - but generally I think yes, Gurbani agrees that there is life away from earth and God has created it.