dans un dossier :

créer background.js
...

créer popup.html
...

manifest.json

{
    "manifest_version": 3,
    "name": "favoris backup",
    "description": "Link to G Suite Certification website",
    "version": "1.2",
    "icons": {
        "128": "icon.png"
    },
    "action": {
        "default_icon": {
            "128": "icon.png"
        },
        "default_title": "Click Me",
        "default_popup": "popup.html"
    },
    "background": {
        "service_worker": "background.js"
    },
    "host_permissions": [
        "https://bookmark.raphaelpiccolo.com/*"
    ],
    "permissions": [
        "unlimitedStorage",
        "notifications",
        "bookmarks",
        "tabs",
        "nativeMessaging"
    ]
}

installer

Aller sur chrome://extensions/
"charger l'extension non empaquetée"