Onboard Graphics Instead of Nvidia GeForce 9400?

ive been using catalina patched for a while with nice stabilty but recently i saw a post on reddit with a 2008 20” imac with big sur patched. of course with the nvidia card there was no graphics acceleration, and i have seen macbook pros disabling their onboard gpu with intels graphics instead. im not sure if the processor in my imac is capable of onboard graphics/even has it.