BetterDummy
Apple Silicon Macs notoriously don’t allow sub-4K resolution displays to have HiDPI (“Retina”) resolutions even though most 1440p display would greatly benefit from having a HiDPI “Retina” mode
https://github.com/waydabber/BetterDummy
MonitorControl
Controls your external display brightness and volume and shows native OSD. Use menulet sliders or the keyboard, including native Apple keys!