Hagoromo only gave them the seals
this ,the seals are what had hagromo chakra ,his chakra wasnt infused with thier chakra,that is why chidori was black only when he said he will use rikudo chakra ,evertime else it was white because his chakra isnt infused with hagromo chakra,he could only use it by drawing it from the seal ,the same with naruto ,the seals is what had hagromo chakra which was latter used to create the moon sized CT ,that explains why thier chakra reserves didnt drop after creating a moon sized CT ,that also explains why momoshiki didnt think of absorbing thier rikudo chakra
Rikudo power up for them was actually the RSM and Rinningan ,Naruto can get some rikudo chakra only by using all biju chakra together just like Jiubi Jin ,that was explained in shikamaru hiden chapter7,while sasuke has the 6T rinningan and its powerfull chakra that only the true owner can has .