I keep a monitor in my server closet and bring a USB wireless mini keyboard if I need to physically access something but the majority of my hardware has KVM built in.

Older commercial hardware uses more power than a mini computer in a homelab but has many advantages like often coming with more ram, more powerful (and often multiple) CPU’s, SAS backplanes, plus empty PCIe slots that can support GPU’s and other devices.

Yep. I’m using sata drives in a SAS backplane that has similar connectors soldered to a board.

The exact backplane I am using is: https://files.ekmcdn.com/itinstock/images/supermicro-sas846a-24-bay-3.5-lff-sas-sata-hdd-4u-backplane-bpn-sas-846a-4-93512-p.jpg

The cable connections don’t mean anything. SAS is multichannel and with expanders (expanders work like ethernet switches) one controller can interface with hundreds of drives.

The cable you have pictured is called a breakout cable that dedicates one of the cards individual channels to a drive. If you plug one drive into the cable and spin it up no big deal, add another later on same thing, move a dive from one cable to the other it’s all good. The cables are just electrical data connections to the controller. With ZFS you can even migrate compatible drives from SAS to SATA controllers (SAS only work on SAS, but sata works on either) in the system and they will still function just fine in a pool. For that matter I’ve heard of people mixing SAS, SATA, and USB drives in the same vDev (not generally recommended) and things worked.