MG Cyberster sets a good example, although it doesn’t seem to be coming to the USA.

There are plenty of examples of Arm machines running at scale now, so that’s a pretty narrow perspective.

£5 for a USB NIC - £100 £3 for a PoE to 5V DC splitter - £60 £2 in short cables - £40 Shelf? £20-50

PoE Switch I already have spare Leaf switch I already have spare Network storage I have in abundance.

Cost wise it’s not prohibitive, about £250

I think the biggest worry is, as you say, it might not be the most stable or impressive compute.

Treat the home network panel as another rack.

Get a patch panel in the server rack and then run a bundle of cables from there to the network panel and plug into a patch panel there.

Neatly tie the cables with velcro cable ties, or cable ties (but that’s less fashionable these days). I’d buy pre-made, others would custom make them to the perfect length to make it prettier

Look at r/cableporn for inspiration, lacing a bundle of cables can be a beautiful thing.