The Local Group affords us the opportunity to study the low-mass extremes of galaxy formation and cosmology. In this capacity, it presents some of the most enduring challenges to the very successful LCDM cosmology. I will discuss to what degree standard theoretical models of the local Universe – including the idea that photoionization heating from cosmic reionization is crucial to suppressing galaxy formation in low mass halos – match the growing volume and diversity of observations in the Local Group and beyond. Since reionization is expected to be a dominant process in determining the abundance of low-mass galaxies around the Milky Way, observations hold the promise to understand aspects of the high-redshift Universe by studying its descendants locally. I will argue that, even in the JWST era, the local Universe may be our best probe of low-mass, currently unobservable galaxies at high redshift that are expected to be crucial for reionization.