Is it possible to get reassigned to another duty station due to pregnancy?

You will not be reassigned from Alaska to Camp Lejune based on your pregnancy.
It is very unlikely that you would ever be assigned to the same installation. This is a reality the two of you should accept now, and develop a course of action

The first thing you need to determine is if there are Army slots for your grade and rank at Camp Lejeune. My guess is no. But i could be wrong. You need to talk to your branch manager and see if there is a location (Ft Bragg) maybe that may be a compromise. There is nothing saying that you will ever be stationed WITH your husband if you are in different branches. Even if your in the same branch there is no guarantee. Talk to your branch and have your husband talk to his Marine Corps equivalent. But if i were you i would be prepared to not be very close to each other for a significant part of your careers. Unless like you said you decide to take a Chapter. I wish you luck.

No it's not, and you are not eligible to PCS until the 7th month after you deliver.

Also, there are definitely no 92A1 positions in Camp Lejeune. Fort Bragg or Fort Lee/Eustis are the closest you will get.
Also the Army will not move you just because you are married. If you are in Alaska you will need to stay there till the end of your DEROS. Your situation does not qualify for a compassionate reassignment and MACP only applies to where you get placed for your next assignment, not to moving you now.

If you want to process a Chapter 8 separation there is a time limit and you will need to be complete and approved prior to the birth of your child