A disk can have a sequential read/write performance of up to 250MB/s. But this can be achieved only when a single user reads/writes a large file like a video to the outer tracks of an empty disk. Real world performance even if they are from larger files are a mix of random and sequential loads so you should count 100-150 MB/s per disk. This means that you need around 6-8 disks in a Raid-0 setup to achieve a real world 800 MB/s.
If you do not care about iops, you can add 2 disks for a raid-6 or raid-Z2 config. If you expect concurrent read/writes you must care about iops so a setup from 12-16 disks in a multiple raid-10 would be the best option. Count around 100 iops from a Raid-6/Z2 (like a single disk as every disk must be positioned in every io). A pool from 6 x mirror would give you around 600 write iops and 1200 read iops in case of ZFS.
Next question is data security in general and in case of a crash during a write. In such a case the content of the write cache is lost. Without a powerloss protection (hardware raid-6 with battery/flash protection or ZFS with a ZIL/Slog) even the raid itself or the filesystem is in danger. If you care about it is very hard to achieve 800 MB)s writes.
What I would use
A fileserver with fast and modern CPU, at least 32 GB RAM, 12-16 disks (HGST HE, SAS) in a multiple Raid-10, a high quality nic (Chelsea or Intel), no hardware raid and no expander but LSI HBAs like 9305-16i with 16 ports or LSI 9300 HBAs with enough ports.
Use software raid, best regarding data security and performance due its advanced rambased read/write cachings is ZFS. To secure writes, you must enable sync write. ZFS with an Optane up from 800P can achieve up to 600-800 MB/s sync write.
Fastest ZFS server OS regarding ZFS, NFS and SMB is Oracle Solaris with a genuine ZFS but this is not free (around 800 USD per year). Next fastest are the free Solaris forks around Illumos, example OmniOS. Next are Free-BSD based solutions. Linux LVM raid over btrfs like Synology is using is far below ZFS in nearly all aspects that affects data security or performance.
Nic aggregation is not needed as a single 10G nic can give more than 1 GB/s. You may enable Jumbo Frames but you this can give more performance but can also give troubles.
see my benchmarks
https://napp-it.org/doc/downloads/optane_slog_pool_performane.pdf
A good professional class server would be an
https://www.supermicro.nl/products/system/2U/5029/SSG-5029P-E1CTR12L.cfm
more hardware suggestions
https://napp-it.org/doc/downloads/napp-it_build_examples.pdf