Use of git-filter-repo as a library in my proprietary, commercial and closed-source software

[suhasdotcom]

Hi Team,
I want to use the dual-licensed git-filter-repo as a library in my proprietary, commercial and closed-source application, by this I mean:

1. I want to sell the application as a binary, executable or package but not disclose its source code.
2. I want to make money from this application.
3. I want to provide warranty and support for this application on various support plans that the users opt-in to.

git-filter-repo is dual licensed as such:

1. Main license file stating that most of the files under the repo are provided under the MIT Licence. I am interested in the git-filter-repo file, which I think is provided under the MIT License.
2. The MIT License file.
3. The GPL License file.

My application project is still in planning phase hence I am experimenting before actual implementation and I do not want to break any license compliances.

There are three main ways in which I plan to use the git-filter-repo software:

1. Call as a subprocess from my application:

   subprocess.run(['git-filter-repo', *args], check=True)

2. As a library:

   import git_filter_repo as gfr

   This means that I may put git-filter-repo as a dependency in my project's pyproject.toml file, as such (experimental):

   dependencies = [
     "git-filter-repo"
   ]

3. As source, Copying the git_filter_repo file (this is the only file I am interested in) into my project and then import it:

   import git_filter_repo as gfr

I need clarification on:

1. Do I need to open source my application if I used any of the above mentioned usages, i.e. subprocess, library or source?
2. If I am required to open souce my project then which license should I use so that it allows me and only me to sell my application as commercial and proprietary so that I can earn from it?
3. Can I still keep my source closed if there is some other way to use git-filter-repo apart from the subprocess or library call?
4. Can I obtain patent on my application design and/or code if I used git-filter-repo internally as mentioned above?

I have already been through:

1. Using an MIT licensed library in my project.
   This question only talks about MIT License and not dual-license and I am not able to understand whether I need to open-source/link the source-code of git-filter-repo alongwith my code's documentation or user manual.

2. Is it legal to use GPL code in a proprietary, closed-source program by putting it in a separate, standalone program?.

   2.a) Do I need to open-source my own application if I used the git-filter-repo as a library or a python import?

   2.b) What are my obligations?

3. How to manage multi-licensed components in a project.
   As git-filter-repo is dual-licensed, according to the answer to the question above, can I assume the MIT-license since it looks more permissive towards closed-source proprietary commercial software than GPL?

Any help is appreciated.