Wordpress

So like, a CMS?

Use Ghost

Not entirely sure I understand what you mean but in addition to the suggestion of WordPress, all the plugins must be licensed as GPL as well. So all the paid for plugins can be obtained and legally used without paying. You will however have to forgo support and automatic updates on most.

I would suggest the WordPress section on babia.to

Wordpress, as mentioned, should cover you for most things, but you have to realise that Wordpress is getting more and more commercialised every day and cheap hosting is probably worse than a bad wordpress site. You can search for free plugins and theme inside wordpress for example, but if you really want to go white label then you will need to look at your own themes or modifying one to suit

Wordpress and Drupal seem to be the most popular. I like both depending on the website.

I'm not sure if I understand completely correctly what white label websites are, but also maybe the themes made for the Hugo website building program?