[callahad]

> A Firefox instance can only run one at the same time, making it useless to run e.g. a work and a private profile together.

I may be misunderstanding what you mean, but I believe you actually can do that. If you navigate to about:profiles, there should be a "launch profile in new browser" button that runs multiple profiles at the same time, each in their own, isolated Firefox process.

To make this a bit easier, you can create desktop shortcuts which launch a specific profile like `firefox --new-instance --profile Work` (on Windows, use --no-remote instead of --new-instance).