Microsoft have released a new ISO for Window 10 20H1 for Windows Insiders. The ISO is build 19041 which will be the build that ships as the April 2020 soon. The ISO is designed for Windows Insiders to test clean installations of Windows 10 and the new ISO replaces the previous build 19035 first released back in December 2019.
Build 19041 was first released to the fast ring December 11th 2019 and then it was released to the slow ring in January. This update was code named 20H1, labeled in the system as 2004 and will probably be know as the Windows 10 April 2020 Update.
You can download the ISO from Microsoft’s download page. You can read all about the changes in the new release on my what’s new page and here is my video review of the changes in Windows 10 April 2020 Update: