https://www.neoaxis.com/ is what you looking for, easy add 3d models and put out a prototype in a few days. You can test the game and see real time changes when you edit stuff.
Viewing post in are there 3d frameworks?
it's a software, it works like Unity where you add C# code on the console or script. The difference is that NeoAxis has support and you can get the source code (AKA the entire program code) if you want to do something beyond for a price while Unity doesn't help you and Unity doesn't give you source code.
If you want something like NeoAxis mixed with Unity, look into https://www.stride3d.net/ it's 100% free, you can edit the source code and you can use Visual Studio.