If you mean “installed F-Droid apps,” if you install F-Droid Classic, which emulates the old F-Droid UI, you will have 3 tabs: Available, Installed, and Updates. I prefer this easy-to-navigate, concise UI to their new one. (I’ve only briefly checked out the new UI, so I don’t know if it has an Installed list somewhere.) You can have both versions of the store on the same phone, so it’s easy to compare them and see which one you like better.
There’s also an app available in F-Droid called List My Apps, which can produce a text file of everything installed on your phone, not just F-Droid apps.
If you ever find that you absolutely need an app that’s available only from Google’s store, and not in F-Droid (or even Amazon, if you’re cool with that), then you might want to install the Aurora app from F-Droid. It can grab packages from Google’s store using its own account, so you never have to sign up to Google.