Going off the local PC only idea, you could script just your rebuilds of them in the off chance something goes south, along with maybe a disk image with the majority of common games loaded. This is just thinking along the lines it's friends and family, not the general public. I'd probably use gigabit Internet (or more) which makes updates you're missing fast, while Steam lets PCs on a LAN share updated files and save bandwidth.
Did you consider patch panels or things like PatchBox to organize those UTP cables or allow for changes in your switching later?
The way I have it set up, I am essentially maintaining only one PC, in a totally normal way. I update Windows by pulling up Windows Update in the control panel, etc. Since I only have to do it for one machine this is fine -- orchestrating updating 20 machines sounds like a pain. Yeah I know there are enterprise tools for this but why bother?
Once I've updated that one machine I just run one command on the server and now all the machines have cloned it. At the end of the party I run one command and all the machines are reverted.
Also I can give everyone full admin access to their machine (which you sometimes need for games) and not have to worry about it, because I know it'll all be completely reverted later.
You could skip the orchestration and remote storage layers altogether and cut your commands you run down to ~0 with local nvme SSDs. What orchestration do PCs running Steam and Epic need? Machines can just auto-update, unless you really like reinventing that or only have a few megabits of bandwidth.
Again, it's not that the netboot setup isn't cool to see built, I was just thinking out loud how to simplify it even further.