Redirects in declarativeNetRequests to Local Resource - google-chrome

Question

I am trying to redirect the request sent to https://site/script1.js to a modified script stored locally chrome-extension://ext_id/my_script.js.
(Basically trying to emulate the behaviour of webRequests.onBeforeRequest -> return redirect to local file)
My rules.json :
[
{
"id": 1,
"priority": 10,
"action":
{ "type": "redirect",
"redirect" : {"extensionPath" : "/my_script.js"}
},
"condition":
{"urlFilter": "https://site/script1.js",
"resourceTypes": ["script"]
}
}
]
If I change the action type to block the chrome dev tools shows the request as blocked, and the website doesnt load, however on redirects, nothing happens and the request goes through. It doesnt work for Images either.
Is there possibly a workaround for this (to modify the script a site receives from a request)?
Edit:
I'll just try to get an image to work first, the declarativeNetRequest Docs single out Redirects for a script.
The website (https://www.example.com/a/b) sends a request to https://cdn.example.com/file.jpg. I want that request to return a file `my_file.jpg' stored locally .
I have :
Rules.json
[
{
"id": 2,
"priority": 9,
"action":
{ "type": "redirect",
"redirect" : {"extensionPath" : "/my_file.jpg"}
},
"condition":
{"urlFilter": "https://cdn.example.com/file.jpg",
"resourceTypes": ["image"]
}
}
]
and Manifest.json includes:
"host_permissions": [
"https://www.example.com/*"
],
"web_accessible_resources":[
{
"resources": ["my_file.jpg"],
"matches" :["https://www.example.com/*"]
}
]