The real value option is buying an older platform (AM4) and a used discrete GPU, from back when prices were more sane.
Power efficiency wise, a discrete GPU won't compare favorably.
Assume mid range 200w gpu. Assume 20 eurocents per kWh (I live in the northern europe and pay about as much on a flexible contract). Assume a decent PSU. A year of gaming (assume, very optimistically, 365hrs) is circa 17 eur for the electricity. Considering relative perf differences, I'd say a discrete GPU compares favourably.
I had a 5700G (I think) last year and the system would go up to 150W max. I could survive about 2-3h of no electricity with my small inverter battery setup if I kept usage minimal (no work, no gaming). Handy performance wise for a mostly work machine with some indie gaming on the side, but these 8000 series are under half that wattage.
Admittedly this isn't the most common need/concern, but it's good to know options are getting better all the time.