Hi! I reached 4th kyu in Kyokushinkai (although trained in it for almost a decade so could have reached a higher grade but chose to take my sweet time), and am currently black belt in Goju. Will try and assist here with what I've experienced!
Yes Kyokushin was born out of Sosai Oyama's experience in Shotokan and Goju. I believe it was more Goju Kai/Yamaguchi (and also from this mysterious fellow named So Nei Chu who I still want to find more information about!!).
I personally experienced little to no "ju" in our Kyokushin training. It really tends to focus alot on strength, power, resilience, spirit, perseverance, heavy contact and so on. We did however work on developing great footwork and sabaki, so it wasn't all just rigid and take every hit. But we didn't focus on internal energy, sensitivity drills or nuance. Just hard hard training, heavy repetitive kihon, kata (no bunkai/oyo) and spirited kumite.
Different strands of Kyokushin may focus on "ju"-related training, and I believe Kancho Hatsuo Royama in Kyokushinkan is big into Taikiken/Ikken training which would awesome to explore.
Different Goju schools will be different, many different lineages etc. Our school are continuous, and most Kyokushin I believe would be continuous sparring as it is reflected in tournaments. Some Goju Kai groups are big into competing so practice alot of point sparring.
Great question, I wish I knew! Perhaps that's why Enshin and Kudo came about... to bring that aspect back into Kyokushin?