For what it's worth, there does exist a fork of Firefox designed with F-Droid in mind (Fennec F-Droid). It's not updated as frequently as the stable browser, but it's updated up to version 1.1 of ever release, has telemetry removed, and even has the "Custom Add-On Collection" feature otherwise exclusive to Nightly.
With this available, there seems little reason for Mozilla to port Firefox to F-Droid themselves.
Alternatively, another app on F-Droid is the "Firefox Updater", which can updated all branches of Firefox (Stable, Beta, Nightly), as well as Brave, Vivaldi, and a few other private options.
I would like to have the official Firefox on F-Droid as well.
I don´t see the connection between Fennec and Firefox, so I don´t trust this app. In addition, F-Droid mentions "unerwünschte Merkmale" (= unwanted features?). I don´t understand why Firefox doesn´t realises an official download on F-Droid.
Maybe can't or will not. Official F-Droid repo will ask for stuff like Trackers or any Google related (even its name that done nothing) removed. That become "Not Mozilla Firefox" anymore. Fennec F-Droid already done the remove Trackers. F-Droid stick with Fennec name and listed without Logo as Mozilla Name and Logo is Trademarked.
F-Droid "Unwanted features" meaning is long and wide. Contacting any Closed Source service to grab and use their database eventhough the main app it self full opensource could be called have "Unwanted features".
1. Mozilla can't do it officially as it have money from Google to put their search engine as default. 2. It's not clear if Firefox Android is completely FOSS so even to start to port it to the main FDROID repo