Is there a way to make MP’s actually really private ? Where an admin can not access other members MP’s unless there’re invited with a flagging or a tag ?

Yes, check Discourse Encrypt (for Private Messages)

Сделайте личные сообщения действительно приватными

Falco (Falco) 03.Декабрь.2020 15:12:00 2

Тема		Ответов	Просм.
How to make it so that admins are not able to view private messages of their users? Support	12	1969	08.09.2022
How alert if admin/mods read users PM? Support	10	1281	16.03.2022
Are PMs truly private and not crawlable? Community Building	4	1305	16.08.2020
Can I view private messages as an Admin? Support	13	5224	14.09.2020
Can true private messages be implemented? Feature	29	5719	09.03.2020