These pico psu are powered by server power supplies. So they can be use for riserless motherboards.
not so they simply can't provide enough power for a lot of slots
My boards use 6 cables for the slots 3 sata and 3 four pin molex
The pico can power 1 of the six slots.
I have built a few hundred mobos and melted more than one pico when trying to run riserless boards.