Looking for Nextcloud desktop developer for MacOS and Windows

Would like to theme nexcloud client and make some modifications in the source code.

Nextcloud GmbH offers branding services for iOS/Android/Desktop in combination with a Nextcloud subscription. You can contact sales {at] nextcloud {dot} com for details.

Thanks for your answer. I’m interested in a specific development which is out of the scope of a simple branding. I’ll contact them to know if they provide such a service.