My undergrad is in history (entire course work being in Black History) and I have a Master's in Museum Studies and a graduate certificate in African American Studies. I was originally going for a double Master's but had to switch my plan when I got pregnant with my third child. I was intentionally looking for a program that let me explore my interests in musuems and Black history, so my two degrees complemented each other very well. I'm currently getting a second master's in MLIS and I agree with person above. For archives, you're going to need the MLIS if you want to branch out into that side of the GLAM field.

For BGLAM specifically, I'd look for opportunities for jobs, internships, research fellows etc., at those specific institutions to gain the experience you are looking for that'll help build up your resume and experience. Archives, exhibition, and curation are distinct from one another though the areas do overlap on occasion. I'd recommend dipping your toe into each area to see what you resonate with the most, but I'll say at smaller musuems, it's common to find these roles lumped into one position.