My advice: if as part of your role you have business requirements that can only be met with Firefox (like ensuring browser compatibility), then ask your manager to put together an exception request, with a compliance plan (e.g. running Firefox on a sandboxed cloud instance).
If you don't NEED Firefox, but WANT it (e.g. based on personal preferences or individual productivity), it will be hard to make a case for it considering that any productivity gain will be offset by increased compliance costs.
I do not advise circumventing company policy since that puts the company itself in jeopardy by potentially being out of compliance with its security policies.
If the company is large, please name and shame (presuming you’re not concerned about being identifiable), but obviously don’t put yourself at risk if you’re not sure this is safe.
Seriously, and I know everyone doesn’t have this luxury, as a dev this kind of thing would pretty much make me leave immediately-it speaks to a certain kind of culture, and let’s just say I’d be a bad fit.
At any rate I will just keep going as is until I get ordered to remove and then make arguments.
I predict that Edge will integrate a lot of contested MS features and in the end will be a horrible browser again. Even know it is bloating up to something else.
I would check the allowed browsers for spy- and bossware though.
Using that when you know the company has told you about their security policy forbidding it is, ummm, not wise. Especially not as a new hire.
If work says "You use Edge, and are not allowed to use Firefox", then you use Edge, or you ask for an exemption from that policy if you have a good reason (and I'd want that in writing if it's an official security policy). Or you get a different job at a company without that policy.