Ok thanks. Yeah I had already looked there, and did the “easy, allowable” customization.
Re-reading it, it suggests contacting “sales” for additional brand theming. When I have more time, I will look more closely at the php code, and figure out how to do it.
If this is all you want (on the webinterface), the “Logo” setting in the Theming section seems to do exactly this. It replaces the Nextcloud logo with your own logo on both the login screen and the header (once you’re logged in). If this isn’t exactly what you want, you can also replace the login screen with an image that displays your brand.
I don’t think you need to go so far as looking at the php code for this but I admit that I might not understand what you want to achieve exactly.