Found at Photovoltaikforum.com: https://www.photovoltaikforum.com/thread/191598-fw-update-offline-deye-sun600g3-eu230-und-baugleiche/?postID=3117643#post3117643
As always: Just don't trust random APKs you find on the internet - This is stored here just for research purposes.