Hi there! NetApp operates in an appliance model, where we need to supply all of the drives for the system and do so with support contracts etc, so it is somewhat different to Synology.
The FAS500f comes with either 24 or 48 x 15.3TB 2.5 inch QLC U.2 connected NVMe SSDs. Formatted capacity of 24 is about 336TB and 48 is about 673TB, however that is only half the story. With NetApp deduplication, compression and snapshot technologies, for general purpose NAS data we expect most organisations will be able to store the equivalent of what other arrays without those technologies would need 1Pb and 2Pb for respectively.
With no cluster environment, you plug the nodes together on the back with loopback cables and the only switches required are for client connectivity, which is 10GBaseT built in with options for 25Gb Ethernet and 32GB FC available.
If you'd like to talk to the field team for your region, please send me a message with your corporate contact details and I can put you in touch with them.
Hope this helps!