Sharing pc memory (dedicated) on rizin 7 5700g (graphics on chip) processor

I'm not too familiar with AMD's graphics on chip stuff but if it's anything like Intel, it should be possible to view in Task Manager:

-Open task manager (ctrl + shift + esc)
-If there's an option for 'More details' at the bottom, click it.
-Click performance
-Click GPU
It will give you details on your GPU memory usage including shared RAM.
Here's a screenshot from my machine (yeah, I know it's quite low end...)