An example shows how to push a single commit with multiple files to an existing branch using PyGithub

multi_file_commit.py

"""
Main Steps:

1. Create blob for each file
2. Create tree with the blobs on top of the specific branch
3. Commit the tree
4. Update the branch to point to the new commit
"""

import os

from github import Github, InputGitTreeElement  # tested with PyGithub==1.54.1

g = Github(os.environ['GITHUB_TOKEN'])
print(f"Authenticated as {g.get_user().login}")

org = g.get_organization('some-org')
print(f"org: {org}")

repo = org.get_repo('some-repo')
print(f"repo: {repo}")

# Create blobs for each file
blob1, blob2, blob3 = [
    repo.create_git_blob(
        content="print('Hello World - 1')",
        encoding='utf-8',
    ),
    repo.create_git_blob(
        content="print('Hello World - 2')",
        encoding='utf-8',
    ),
    repo.create_git_blob(
        content="print('Hello World - 3')",
        encoding='utf-8',
    ),
]
print(f"blob1: {blob1}")
print(f"blob2: {blob2}")
print(f"blob3: {blob3}")

# Create a new tree with our blobs
new_tree = repo.create_git_tree(
    tree=[
        InputGitTreeElement(
            path="hello-world-1.py",
            mode="100644",
            type="blob",
            sha=blob1.sha,
        ),
        InputGitTreeElement(
            path="hello-world-2.py",
            mode="100644",
            type="blob",
            sha=blob2.sha,
        ),
        InputGitTreeElement(
            path="hello-world-3.py",
            mode="100644",
            type="blob",
            sha=blob3.sha,
        ),
    ],
    base_tree=repo.get_git_tree(sha='hello-world')
)
print(f"new_tree: {new_tree}")

# Create a new commit with that tree on top of the current hello-world branch head
commit = repo.create_git_commit(
    message="Add multiple files",
    tree=repo.get_git_tree(sha=new_tree.sha),
    parents=[repo.get_git_commit(repo.get_branch('hello-world').commit.sha)],
)

# Push that commit to the hello-world branch by editing the reference
hello_world_ref = repo.get_git_ref(ref='heads/hello-world')
print(f"hello_world_ref: {hello_world_ref}")

hello_world_ref.edit(sha=commit.sha)

print("DONE")

Awesome. Saved me a lot of work with this example. Thanks @ohaval

yes, thanks @ohaval for the time savings!!
a twist on this code for multiple files, I created a tree_list variable and append the new blob and tree elements in a loop.