Not that you're wrong, but galaxies in our neighborhood aren't really of concern to Euclid. The mission is to determine the expansion history of the universe, for which we will observe billions of galaxies. The handful of galaxies in our local group, which don't contain any information about the expansion history anyway, are less than a drop in the bucket.

Also, frames can just be stitched together if necessary. And Andromeda is larger than the field of vision of Euclid.

A large field of vision just helps you cover a large amount of sky in a reasonable time frame.