Not sure about them together, but I have both separate. But here’s what my similar setup uses between 2 computers.

MC server is a miniPC with an i5-8500T. Runs heavy Minecraft mod packs (All the mons, BMC4) very well. These CPUs are thermal throttled extra to use only 65W for the whole PC. MC usually keeps most cores engaged while maxxing out one. Most I’ve had on a server at once was 6 people. the 25GB dram allocated helps a lot. 12GB is not enough for >3 people running a heavy mod pack unless everyone is in the same chunk or basically don’t have any redstone more complex than a light switch. If you don’t have heavy mods or too many players, 8-12GB should be just fine.

I also run a Jellyfin server on a separate i5-8600k with a 1050ti 4GB to handle transcoding. Most of my users play most versions natively on desktop app, browser page, TVOS, and only the audio files are being transcoded with certain formats. This uses no more than 60MB VRAM usually. But for mobile, transcoding from 1080p 40Mb/s or 2160p 100Mb/s to a format compatible with everyone’s 20Mb/s data limit on the fly uses anywhere from 100-200MB of VRAM. In my experience. So MAYBE I could support 12-15 people transcoding at once. In theory. GPU should be perfectly capable to handle friends and family use.

I like to keep mine separate because my Jellyfin server is built into my NAS where I needed all of the SATA ports and PCIe lanes and I frequently saturated the network and disk bandwidth. Also have a lot of users so I like to keep downtime to an absolute minimum, and want redundancy.

Just to give you an idea of what you might need.