How to get tab/url's favicon in safari web extension natively?

I'm converting a Chrome Extension to a Safari Web Extension, I found it's not easy to get favicon of current tab/url natively.
  1. The tab object in Safari doesn't have favIconUrl.

Code Block json
{
"id": 121,
"index": 6,
"active": true,
"width": 1324,
"audible": false,
"url": "https://github.com/",
"mutedInfo": {
"muted": false
},
"windowId": 2,
"title": "GitHub",
"incognito": false,
"pinned": false,
"height": 935,
"highlighted": true,
"status": "complete"
}

2. I didn't find Safari has similar thing like chrome://favicon

3. I found Safari's favicon caches in ~/Library/Safari/Favicon Cache/favicons but have no idea how to use them in Safari Web Extension.

Am looking for FavIcon API too, where I can change them from safari extension. Best would be to get data_uri-mime-base64 type image of favicon and possibly way to write it back.

How to get tab/url's favicon in safari web extension natively?
 
 
Q