Questions[proprietary](ubuntu)

During the installation process I can check the box Install third-party software for graphics and Wi-Fi hardware and additional media formats. [...] Some is proprietary. I think there might be some drivers then that are proprietary. Also, if I install apps manually, there might be some that are not open-source.

However, which other parts of Ubuntu 20.04 are proprietary by default?

Debian's documentation does mention that:

Please note that the number of non-free and contrib packages is less than 2% of that of main packages.

Debian have three components of repository: main (which include 100% free softwares), contrib (which includes free softwares that depends upon non-free softwares) and non-free (which contains proprietary softwares). So, the documentation is saying that less than 2% of that of main packages are contained in non-free and contrib repositories.

I want to know the same thing for Ubuntu. Ubuntu has free softwares on main and universe repositories and restricted and multiverse components of repositories contain non-free softwares.

Now, how much percentage of non-free softwares are contained by these restricted and multiverse repositories compared to that of main and universe repositories? Do we have any such analysis?

I know I can check the currently installed non-free software with the following command (assuming aptitude is FOSS):

aptitude search '?installed (?section(restricted) | ?section(multiverse))'

And I can remove the "restricted" and "multiverse" sources (and not add any PPA's) to keep that list empty. I'm assuming from this point, whenever I apt install something, that something is either in the allowed sources or it is not found.

Is this enough? Does this make sure all software I'm running (in Ubuntu) is open-source?

Laptop: Acer Predator with Ubuntu 18.04 LTS and Windows 10 (dual boot)
Specifications: Intel® Core i7-7700HQ NVIDIA GTX 1060 OS-Type: 64-bit

Everything is working fine so far, except that I can't switch to the NVIDIA graphics card in Ubuntu. Please help me, this is the first time that I have installed a Linux distribution on my PC.
I was following the installation tutorial from this website, I can't get it to work.

I have tried to install the NVIDIA drivers from the Ubuntu repositories and from the GPU Drivers PPA.
I have read many threads and tried to follow the suggestions. But same results, nothing is working. Below is a detailed step by step of the last commands I ran in the order they were executed.

1. Purge everything NVIDIA:

   sudo apt purge nvidia-*  
   

2. Purge the PPA:

   sudo ppa-purge ppa:graphics-drivers/ppa    
   

3. Autoremove:

   sudo apt autoremove
   

4. Clean up:

   sudo apt auto-clean
   

5. Blacklist Nouveau:

   Edited the file /etc/modprobe.d/disable-nouveau.conf and added these lines:

   blacklist nouveau
   blacklist vga16fb
   blacklist rivafb
   blacklist nvidiafb
   blacklist rivatv
   blacklist amd76_edac
   alias nouveau off
   alias lbm-nouveau off
   options nouveau modeset=0
   

6. Re-add the PPA:

   sudo add-apt-repository ppa:graphics-drivers/ppa
   

7. Check for recommended drivers:

   ubuntu-drivers devices
   

8. Install the recommended driver from the PPA:

   sudo apt install nvidia-driver-396
   

9. Reboot the system:

   sudo reboot
   

10. Check which drivers are in use:

    $ lspci -k | grep -EA2 'VGA|3D'
    00:02.0 VGA compatible controller: Intel Corporation Device 591b (rev 04)
        Subsystem: Acer Incorporated [ALI] Device 118a
        Kernel driver in use: i915
    --
    01:00.0 VGA compatible controller: NVIDIA Corporation GP106M [GeForce GTX 1060 Mobile] (rev a1)
        Subsystem: Acer Incorporated [ALI] GP106M [GeForce GTX 1060 Mobile]
        Kernel driver in use: nouveau
    
    $ lspci -nnk | grep -i vga -A3
    00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:591b] (rev 04)
        Subsystem: Acer Incorporated [ALI] Device [1025:118a]
        Kernel driver in use: i915
        Kernel modules: i915
    --
    01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GP106M [GeForce GTX 1060 Mobile] [10de:1c20] (rev a1)
        Subsystem: Acer Incorporated [ALI] GP106M [GeForce GTX 1060 Mobile] [1025:118b]
        Kernel driver in use: nouveau
        Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia
    
    $ nvidia-smi
    NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver.  
    Make sure that the latest NVIDIA driver is installed and running.
    
    $ nvidia-settings
     ERROR: NVIDIA driver is not loaded   
     ERROR: Unable to load info from any available system
    

My question is very simple: how to get rid of proprietary software from the Ubuntu Software Center (USC)?

It doesn’t work to enable or disable repositories. Even with just the “universe” and “main” repositories active you can still see plenty of proprietary software. Examples include Skype, Slack, Spotiffy.

Tested: Ubuntu 18.04 and Ubuntu 16.04.

Edited: I had to edit this question down to exclude another bug that I previously reported here about how many open source apps in the USC are mislabeled as proprietary. Added that here https://askubuntu.com/questions/1052688/open-source-software-mislabeled-in-ubuntu-software-center-usc-as-proprietary

UPDATE: This question remains unanswered and I believe it is a very important topic so it needs more attention. If Ubuntu claims to be Free and Open Source then give me the freedom to remove the proprietary software from your official Software Center please. Newcomers to Ubuntu Operating System will not know how to avoid the proprietary apps from the Software Center, especially since when they (I, and all of us) install Ubuntu we may choose only the Open Source repositories, yet the Software Center is full of proprietary apps.

UPDATE 2: 33% of the software is proprietary when you visit the USC home. Video https://www.youtube.com/watch?v=PIVHQj7pfXQ&feature=youtu.be Also Krita appears as proprietary and I reported here Krita labeled as proprietary in Ubuntu Software Center