Hi and welcome to the Forum!
I definitely don’t want to kill your spirit and motivation, just asking to better understand.
Isn’t the company Nextcloud GmbH already presenting Nextcloud to the users and the advantages of this software above Google Drive and Co.?
In case this is what you are seeking for, then there is a lot of material on the nextcloud web site.
What comes to my mind regarding advertising Nextcloud to users, is the aspect of language. All the ads and blog posts and “What’s New” is usually in English. Most people I’d like to advertise Nextcloud to, don’t speak English however.
Nonetheless, when you finished your howto, we could add it here probably: