As a user i would like to use Passbolt in Firefox's sidebar

Q1. What is the problem that you are trying to solve?
Using vertical tabs, on Firefox, browser extensions that support it have a dedicated area where their icon can be displayed. Clicking on such icons will open the extension on a side panel instead of a pop-up.
At the moment Passbolt doesn’t support this, it would be an improvement if it did as to provide a more customisable user experience.

Q2 - Who is impacted?
I’m guessing not many people use vertical tabs, this would however benefit them.

Q3 - Why is it important and/or urgent?
This is neither, however it should, in theory, be a quick fix

Q4 - What is your proposed solution? (optional)
It should be enough to add this section to Firefox’s manifest.json:

"sidebar_action": {
  "default_icon": "webAccessibleResources/img/icons/icon-32.png",
  "theme_icons": [{
    "light": "webAccessibleResources/img/icons/icon-32.png",
    "dark": "webAccessibleResources/img/icons/icon-32.png",
    "size": 32
  }],
  "default_title": "Passbolt Quickaccess",
  "default_panel": "webAccessibleResources/quickaccess.html?passbolt=quickaccess"
},

Q5. Community support
It says I cannot create polls

Hello @nicolabba

You not create a poll yet, but if your code is enough to make it run on Firefox, I suggest that you create a Pull Request there
https://github.com/passbolt/passbolt_browser_extension

Cheers