They all seem reasonable suggestions:

• Consent matters, even for public posts
• Get broad feedback before launching – and listen to it
• Honor existing opt-in and opt-out mechanisms
• Include an additional opt-in mechanism for your service if it’s not just a search engine or profile discovery (or something very close to them)
• Make sure to communicate that you’re taking an opt-in approach and honoring existing mechanisms
• DON’T say the things that developers who ignore consent typically say
• Be extra careful if you’re a cis guy
• Look at opt-in as an opportunity for a potential competitive advantage

I’m conflicted over the fact that using ActivitiyPub necessarily implies consent for other people to collect the data you send through it. It seems that many people using ActivitiyPub connected services want something different than ActivitiyPub or different default settings on many ActivityPub services.