The general answer to this question is "Use any equal area projection in units of meters that covers the world". Python code needed to make use of this is short and sweet:
import geopandas as gpd gdf = gpd.read_file("my.geojson") equal_area_crs = "EPSG:????" areas = gdf.to_crs(equal_area_crs).area
I found myself very frustrated however that googling this phrase (and many variants of it) produced zero useful results on the first page. There are MANY introductions to the basics of projections but no quick answers I could use to quickly fix a bug that used an improper area distorting projection.
Searching on epsg.io is somewhat inflexible, seeming only to search in names. A search for "equal area" or "lambert azimuthal equal area" and a variety of other equal area searches produce results with specific regional applicability and mixed units.
I'm posting here because it took me a full hour to find a satisfactory answer, and this may be useful to others.