Firefox Excel extension

I want a Firefox extension that will do the following:

1. I will paste in the name of a page into Firefox for a reddit user. For example, reddit.com/user/alanltycz/

2. When the page opens, I press the F10 key , and the extension gits the following data from the Reddit page: Post Karma, Comment Karma, and Cake Date. In the example provided, the corresponding values are: Post Karma: 596, Comment Karma 1036, Cake Date: 10/22/2019. Note: I do not need the hours/minutes/seconds values.

3. I will then switch to an Excel document, click in the document where the first item is to be pasted, for example, cell E1. When I paste, it will paste the Post Karma value into E1, the Comment Karma value into E2, and the Cake Date value into E3.

The Extension can be unsigned. I can load it each time via 'about:debugging'.

Note: I am not tied to the F10 key, if it is in use for some other critical function in Firefox.

Note: I expect to have multiple tabs open with different Reddit users. The extension has to work on a per-tab basis.