I just run them side by side on the same nuc. All my friends still use Plex though I think because the apps look nicer. I wish jellyfin had federated features so that you could choose to use a single account across many friends instances. I still use Plex because I don’t want to deal with syncing watched status between instances.
I can’t help with the 2 options you presented, but if you’re interested in an sfp+ router, I’ve used the DEC2750/DEC750 from OPNsense as a directly fiber connected router for Comcast Gigabit Pro 2Gig fiber for several years. It’s super capable, you’ll have an enormous state table to accommodate tons of P2P connections for torrenting, and you’ll be able to enable loads of plugins, VPN connections, IDS, etc without the CPU breaking a sweat.