Anchor ships as two apps because parental control on Android actually needs to be two apps. The kid's device runs an enforcement runtime that has to live deep in Android: a persistent background service, schedule evaluation that fires on time, tamper detection that catches the bypass routes kids try. Your phone is a control surface: sign up, set rules, see what's happening, generate codes when your kid asks for more time.
Bundling those two responsibilities into a single app forces a compromise that breaks at least one of them. Either your phone installs enforcement permissions it does not need, or your kid's device runs a parent-grade dashboard it does not use. Anchor avoids that compromise by keeping the two roles on the two devices where they belong.
This is also the architecture Google's Families policy expects for parental controls. Every major Android parental control product ships as a companion-app pair for the same reason: the responsibilities and permissions live where they are actually used.