I linked both prebuilt and do it yourself builds. Neither resulted in a comparable machine to the PS5 for $600.

Again, I think you are missing how much the price of components has increased.

16GB of DDR5 alone costs approximately $200 [1]. I challenge you to find a new case, motherboard, NVMe SSD, and PSU for the remaining $100 in the budget after $200 for ram and after your assumed $300 for a GPU.

[1] https://pcpartpicker.com/products/memory/#b=ddr5&Z=16384001,...