@glennf Thanks for all the guidance in Take Control of Your Apple Account (a title which I wouldn’t have believed could be a book 10 years ago but here we are). In case you want to note it, the thing blocking me from migrating my purchases & subs from my 2nd account was: I had TestFlight apps subscribed in the primary account. Canceling each TestFlight in the Testflight app got the elusive Migrate Purchases button to appear—per an Apple Support rep suggestion.