I want to be logged in so I can do most things on Reddit like post and comment. I want it to be a web frontend rather than an app because I keep many tabs on Reddit open in my browser while doing research on things (like digital privacy for instance!). I did some searching and didn’t find any currently working frontends with login support.
Unfortunately, that doesn’t exist without the API. You could use the normal frontend and container tabs for ff. They are an extension, but it’s made by Mozilla and integrates quite well. You can even automate it so Reddit always opens in a specific container.