Can I use npm instead of yarn

Yes, just remove the yarn.lock file.

What will be included in the npm bundle?

All filles listed in the files property of your package JSON.

How to debug the action

You can increase the verbosity by creating a new secret ACTIONS_STEP_DEBUG and setting it to true.

Disable linting and formatting

Remove this, this and this from your package.json
Remove this and this from github/workflows/ci.yaml
Remove .eslintignore, .eslintrc.js, .prettierignore and .prettierrc.json.

Accessing files outside the dist/ directory

The drawback of having short import path is that the dir structure
is not exactly the same in production ( in the npm bundle ) and in development.

The files and directories in dist/ will be moved to the root of the project.

As a result this won't work in production:

src/index.ts

import * as fs from "fs";
import * as path from "path";

const str = fs.readFileSync(
    path.join(__dirname,"..", "package.json")
).toString("utf8");

Because /dist/index.js will be moved to /index.js

You'll have to do:

src/index.ts

import * as fs from "fs";
import * as path from "path";
import { getProjectRoot } from "./tools/getProjectRoot";

const str = fs.readFileSync(
    path.join(getProjectRoot(),"package.json")
).toString("utf8");

With getProjectRoot.ts being:

import * as fs from "fs";
import * as path from "path";

function getProjectRootRec(dirPath: string): string {
    if (fs.existsSync(path.join(dirPath, "package.json"))) {
        return dirPath;
    }
    return getProjectRootRec(path.join(dirPath, ".."));
}

let result: string | undefined = undefined;

export function getProjectRoot(): string {
    if (result !== undefined) {
        return result;
    }

    return (result = getProjectRootRec(__dirname));
}

How does the automatic CHANGELOG.md update works?

Starting from the second release, a CHANGELOG.md will be created at the root of the repo.

Example:

The CHANGELOG.md is built from the commits messages since last release.

Are NOT included in the CHANGELOG.md:

• The commit messages that includes the word "changelog" ( non-case sensitive ).
• The commit messages that start with "Merge branch ".
• The commit messages that with "GitBook: "

The GitHub release will point to a freezed version of the CHANGELOG.md: