Authorize a Nextcloud agenda to show in another website

Hello,

I’m not providing all the tech information as I think it’s not exactly relevant to my question (I can say up to date NC with agenda).
I’am asked about the possibility to display a Nextcloud Agenda into the page of a web site (using Spip CMS, but question is any CMS in fact).
My first idea was to use an iframe with some CSP tweaking:

On the website domain.tld
Header always set Content-Security-Policy “frame-src https://sub.domain.tld;”

Nextcloud sub.domain.tld
Header always set Content-Security-Policy “frame-ancestors https://domain.tld;”

But I read that CSP headers are handled by Nextcloud PHP and apparently cannot be modified (using for example config.php).

So my questions are:

  • is it possible to make changes to Nextcloud CSP headers ?
  • or is there another way to achieve this, ie including a NC agenda in a regular website page … I was thinking about some kind of javascript widget ?

Any idea would be welcomed, thanks !

Pierre