Item 2 would definitely be relevant if one was testing Bluetooth device compatibility or multi-display functionality; for general software testing with a wired

Item 2 would definitely be relevant if one was testing Bluetooth device compatibility or multi-display functionality; for general software testing with a wired keyboard and mouse via HDMI and wired Ethernet (a testing scenario that minimizes any latency), it's not so much of an issue. I agree with the M1 Mac mini 8/256 recommendation, though it represents a plateau of performance that many of the remaining (and many) Intel macOS devices cannot reach. The M1 is faster, therefore perhaps not as representative of currently-supported legacy macOS-on-Intel devices.