I would do pretty much what I do now with two mini PCs and my desktop PC running background services in a three node cluster. I change my mind too often though and just did a bit of a rebuild over the holiday, so by next weekend I may have a completely different goal.

I having considered replacing the desktop with a laptop for more portability.

I would also not mind getting a 2.5 Gbps switch. I have all 2.5 Gbps devices on the network except the switch which is a little silly.

You could try fan swaps and sound dampening but it can easily end up costing more in money and time researching compatibility than what some of these servers are worth.

Starting small is what I recommend. I had a rack before. Now I just run mini PCs.

Cheap mini PCs have been my goto.

They are often powerful enough to get the job done, small, low power, quiet, and are easy to ship to sell if I want to upgrade. They may not be as reliable but I did the work on the software side to be able to easily replace or add new nodes.