Offering my experience as an example: I’m a software moron (fine at building a pc, crap at using it) and TrueNas Scale was simple to install and then access on mobile, tablet and via windows PC, at least as simple network attached storage.
When I tried to use it to just jellyfin I hit a brick wall, completely unable to understand how to use the shared datasets.
But as NAS it’s simple with a bookmark to manage.
TrueNAS scale, LIS HBA cards, server motherboards with plenty of PCI Lanes ie AMD EPYC, large capacity HDD, just make sure they are CMR and not SMR drives. And Raidz2 is your friend. You will not need 40 drives, frankly you will fit 10,000 films, mostly 4K and 1000 complete TV series on a single 12 drive wide Raidz2 vDev using 20TB drives. That’s enough to last 50 years in terms of viewing time.