a comparison: with a mountain harness you have a sink rate of around 1.15 m / sec. with a paramotor such as x4, scout, sp 140, miniplane you have a sink rate of 1.5 to 1.6 m / sec.
This means that the thermal must be at least 35% better for the pilot with paramotor in order to be able to maintain the same altitude as the pilot without paramotor. there is a lot of difference!
i was once near alps at a meeting of the mountain pg pilots and was allowed to fly there with standart eppg. so i could compare myself with motor off and thermal circuits. the thermal was very weak. all pilots without eppg were able to maintain the altitude for a long time and it was easy for beginners to do that too. I struggled a lot to keep myself up. but didn’t make it. you noticed the difference very quickly in each circle.
my opinion: if the thermals are extremely good, professional pilots can also fly thermals with eppg. in normal or weak thermal conditions, hobby pilots will not be able to stay up for long. the only possibility is to aerodynamically imitate the system of an motorless pg in order to achieve a sink rate of less than 1.2 m / sec.