YouTube
Two separate YouTube integrations, grouped under one "Google" row in + Add integration alongside Drive, Calendar, Mail, and Photos - one watches any public channel, the other signs into your own account.
Channel
Watches any public YouTube channel using just a Google API key - no sign-in required, since it only reads public data. Reports Subscribers, Videos, and the channel's latest video (title, ID, and publish time), so a new upload can trigger an automation.
Account
Signs into your own YouTube/Google account (a real OAuth2 login) to report your own channel's My subscribers and My videos counts, and adds an Add to playlist automation action for adding a video to one of your own playlists.