The verdict

CPU
Beelink GTR9 has 1.9x the CPU throughput (54,968 vs 29,364 PassMark).
Idle power
Minisforum UM890 Pro idles lower (9W vs 16W) - cheaper to run 24/7.
RAM ceiling
Beelink GTR9 takes more RAM (128GB vs 96GB).

Which wins for each job

Job Beelink GTR9 Minisforum UM890 Pro
Plex / Jellyfin ~5 streams ~5 streams
Frigate NVR add a detector add a detector
Proxmox / VMs 54,968 PassMark win 29,364 PassMark
Firewall / router 2 NICs 2 NICs
Local AI / LLM no slot no slot

Approximate - capacity estimates from curated specs, the same logic as the recommender. Verify against your exact setup. Prices move; check the retailer.

Full specs

Spec Beelink GTR9 Minisforum UM890 Pro
Price (list) $1,985 $479
CPU AMD Ryzen AI Max+ 395 AMD Ryzen 9 8945HS
Cores / threads 16 8
PassMark 54,968 29,364
iGPU Radeon 8060S (RDNA3.5) Radeon 780M (RDNA3)
NICs 2 2
NIC model Dual 10GbE Realtek RTL8125
RAM max (GB) 128 96
M.2 free 1 1
PCIe slot none none
Idle (W) 16 9
TDP (W) 140 54