Yeah, getting a 4-port 10Gbe card would be ideal, but I don't think the T730 cooling or power delivery can handle it, so I may just go with plain ol' Gigabit.
I overspent like $700 on my first pfSense build in 2013: Xeon CPU, 2x8 GB of DDR3 ECC RAM, Supermicro motherboard for 4-port Intel i210 Gigabit NICs, 2U Rosewill rackmount chassis. It was rock solid but a lightning storm in 2019 destroyed it (the surge entered the house through coax cable then traveled through the cable modem and fried everything attached to Ethernet.)
While my ultimate goal is to someday build a solid 1U Supermicro pfSense router that has plenty of 10Gbe, SFP+, and 25-Gig (SFP28) connectivity, something like that would be over $1000, and I'm currently renting and we're on 200/20 Mbps cable Internet and the house is not wired for Ethernet yet, so the HP Thin client idea seems cheap enough for current needs.
I mainly used pfBlocker with lots of malware filtering rules, no Snort/Suricata yet (learning curve and fine-tuning!), and 24/7 OpenVPN gateways with policy-based routing for all my WAN traffic, and FreeRADIUS for WPA2-Enterprise EAP-TLS WiFi (certificates everywhere and mutual auth). I can't wait to have pfSense running again so I can switch from WPA3-PSK to WPA3-Enterprise
I should be good with the 8 GB RAM in a thin client build and in the future I can re-purposes the machine as a small Proxmox device or something. I've been putting off my pfSense rebuild for almost 4 years now.
But I digress. Fold on!