Can I assign a browser to open links from specific apps?

I'm on Ubuntu 20.04.

I'm using Firefox as my main browser. I've set it up to auto delete cookies and disabled Javascript to make browsing more secure and private.

For my work I'm using Brave. Is it possible to set up Ubuntu so that it uses Brave as the default browser to open links from Slack and my work mailbox in Thunderbird but keep Firefox as the default for everything else?

My answer may disappoint, but it is my take.

Not easily, or not really. You can only have one browser to be the system default. If you would want a different browser to open in a specific app, then you depend on that app providing a possibility to configure this. Usually that will not be configurable in a specific app.

Usually, you will be able to right-click a link and copy it to the clipboard. That would allow for a manual way to open it in a different browser.