CRS for BBox and data

[danlooo]

How do we want to handle the projection used for input arguments, processing and output?
The raw data is in Equi7Grid. If we want a scaleable workflow, the output should be in Equi7Grid as well.
On the other side, users might want to use lat/lon BBox for input arguments.
We can convert between them easily using proj:

AF: '+proj=aeqd +lat_0=8.5 +lon_0=21.5 +x_0=5621452.01998 +y_0=5990638.42298 +datum=WGS84 +units=m +no_defs'
AN: '+proj=aeqd +lat_0=-90 +lon_0=0 +x_0=3714266.97719 +y_0=3402016.50625 +datum=WGS84 +units=m +no_defs'
AS: '+proj=aeqd +lat_0=47 +lon_0=94 +x_0=4340913.84808 +y_0=4812712.92347 +datum=WGS84 +units=m +no_defs'
EU: '+proj=aeqd +lat_0=53 +lon_0=24 +x_0=5837287.81977 +y_0=2121415.69617 +datum=WGS84 +units=m +no_defs'
NA: '+proj=aeqd +lat_0=52 +lon_0=-97.5 +x_0=8264722.17686 +y_0=4867518.35323 +datum=WGS84 +units=m +no_defs'
OC: '+proj=aeqd +lat_0=-19.5 +lon_0=131.5 +x_0=6988408.5356 +y_0=7654884.53733 +datum=WGS84 +units=m +no_defs'
SA: '+proj=aeqd +lat_0=-14 +lon_0=-60.5 +x_0=7257179.23559 +y_0=5592024.44605 +datum=WGS84 +units=m +no_defs'

And how about the output format? Zarr with dimensions (continent,x,y) and chunking by tile or (continent,tile,x,y)?