I would like to know if running CheckMK behind an NGINX reverse proxy is supported and if yes, is there some sort of documentation im not finding? ^^
There reverse proxy exists because company-traffic should always traverse through it and having checkmk standalone has brought unwanted attention in my company 
Thanks for any feedback as always ^^
It is not supported. However, there are plenty of users who do it. Maybe one of them can point you in a direction, as there is no official documentation. But it should be fairly easy to set up. Just be aware, that in support we cannot help you with web server specific issues in that setup.
its not supported and nothing I would recommend. we ran the GUI of or main site behind a HA Proxy but removed it.
Please bear in mind that agent communication might also go this way, for example agent updates, agent registration etc. that will have a significant impact if you run a large environment