You definitely can. You will lose some functionality in the app/web portal but its worth it if you know what you’re doing.

Yes, get your own router, don’t use the app. If you’re technically inclined, the app will only restrict what you can do with the equipment. And with ISP owned equipment, they have api access to your equipment.

Let’s be clear here too. There was real dissent in Germany and the Nazis shipped those who fought back to camps first. These people just doing their jobs made their choice.