How do I enable hardware acceleration when deploying to device?

I am developing a xamarin forms application right now and I have some problems with hardware acceleration.

Specifically, in the android emulator, hardware acceleration works, ie

System.Numerics.Vector.IsHardwareAccelerated

returns true.

On the device however, it returns false, and thus libraries like ImageSharp are super slow.

I already checked the build settings and "Optimize code" is checked everywhere. Also I added HardwareAccelerated = true to the MainActivity.cs in the android project, but that doesn't change anything.

The phone I am using is the OnePlus 5, and the Android version on the phone is 8.1, on the emulator its 7.1.

Anybody can help?

Cheers, Johannes