Honestly, I could do and have done Unreal, Unity and (easily) Godot development on less!
But that’s the minimum to spend for a very comfortable experience, I’d say; RX7900 and GTX 4090 are only there for bragging, while an on-board GPU would not be comfortable running game graphics in my opinion but I’ve seen people do it and not complain :/
Good job! I’m proud of you!
That’s how I usually make it, as well!