[help] could use some parts advice on building a diy nass for docker/media

hi i would like to build a media/download/nass that more expandible drive wise (needs to be able to stream media(jellyfin /use docker containers and have 3 a4 sata ports)

i currently im thinking on buying this motherboard/with built in cpu asrock-j3455-itx-mini-itx- and planning on adding cheap 16 gig ddr3 stics

the nice thing is its got 4x sata 3 ports and a m.2 for like 65 euro total

so my question is should i get one .if its still wort it .and would this work with my specified needs also what do i use as a psu /how much psu power do i need for 4 drives

and what are my exspansion options with the picie .and m2

would love to ad more sata conections trough the m.2 and pcie if posible

i kinda need a nass/media dowload pc /that has a few sata ports .and can run sonarr/prowlarr/jellyfin /qbittorent -running dietpi os /or debian

and run a few ssd/or/hd drives in raid 0 that is about it (ive have no need for drive redundancy thb it all gonna be torrented anime anyway) best leave no evidance of pireacy lol