Realtek itself has demonstrated its RTL8127 NIC working with an unknown switch using cheap CAT5E cables, and the company’s representatives at the booth emphasised this fact. However, we do not know which switch or router the company used. Yet, most 10GbE routers and switches are designed for CAT6 cabling.
Funny update about the cabling they used during the demo. There's really no reason Cat 5e couldn't work for short enough distances with little interference. It's more about the guaranteed minimum distance you can get, 55m with Cat 6 and the full 100m for any rating beyond that.
It's really a wild growth over the years. My current approach is twofold. Netbox to manage devices/VMs and associated info with service deployments using Ansible. You can use the info from Netbox as an Ansible inventory directly.
Previously I tried network diagrams (too low detail) and spreadsheets (terrible to modify) to document machines. And for serviced I'd have an install page on my wiki (apologies, the codeblocks are somewhat broken atm)
An SFP+ single mode module alone costs ~20€ at least. Add to that a PCIe extension card and you're way over the cost of copper.