The degree is whatever you want to deal with. I had a rack at my last house (need to redesign the space for it at new house) with 3x Dell R620s in a Proxmox cluster, running K8s, serving Ceph from NVMe drives over Infiniband (for the mesh traffic), and 2x Supermicros running independent ZFS pools.

It was fun to build - especially Infiniband - but my next iteration is going to be a single beefy server, maybe with storage attached externally. What I had had outstanding uptime, but ultimately it was massively overkill, noisy, hot, and sucked power down.

You sure can. Pi are pretty underpowered you can get machines with more cores and memory and pcie lanes and networking out there and virtualize them

I paid 150€ for a Mini PC with an Intel N100, 16 GB of DDR5 memory, and a 500 GB SSD.

While I have no intention to scale up low spec hardware like this, it at least seems to beat the Azure VMs we use at work with "4 CPUs", which corresponds to two physical cores on an AMD EPYC CPU.

And that super slow machine I understand costs more than $100 per month, and that's without charges for disk space slower than the SSD, or network traffic.

Renting at Azure seems to be a terrible decision, particularly for desktop use.