Not the only way. I used to use ddctool [0] to change brightness on monitors and it worked even with some cheap old Benq displays. Unfortunately Linux doesn't support DDC over DisplayPort Multi-Stream Transport, but you won't need to worry about that. All you need is some Windows alternative to ddctool. This was the first search hit: https://www.clickmonitorddc.bplaced.net/
Yeah it's not the only way. Windows actually provides and easy-to-use API to change screen brightness (since it's a standardised feature). I made a little physical knob that connects via USB to control mine since those capacitative buttons are a right pain.
- updates served via HTTP through the browser only
- as a binary (exe)
- from a domain other than dell.com (delldisplaymanager.com)
- signed by a 3rd party (En Tech Taiwan)
- and nagging about updates every reboot
(you can get an outdated version via dell.com, but it will want to update through said channel immediately)
(And I bet this one gets pinged for updates, having the full url to the exe in the update check: https://www.entechtaiwan.com/updates/public/ddm.inf )