Firefox has something called multi-account containers (this is technically an extension but it's developed by Mozilla) that lets you basically have profiles but on a per-tab basis instead of a per-window basis. It color-codes the tabs to let you know which container it's running in, and you can set it up to always open a given site in a particular container if you want.

Here's the help page if you want more info: https://support.mozilla.org/en-US/kb/containers