Mozilla has been working on a rethought version of Firefox for Android for more than a year already, and things are starting to fall into place. In February, the browser received support for its first add-on, and now, two months later, Mozilla has announced that the Nightly release of the Preview software works with five more extensions.
On the privacy and security front, NoScript, HTTPS Everywhere, and Privacy Badger are available. NoScript prevents potentially malicious code from running on websites you don't trust, HTTPS Everywhere upgrades all of your supported connections to the more secure HTTPS encryption, and Privacy Badger blocks invisible web trackers (side effect: way fewer third-party ads). There's also Dark Reader, an extension that automatically creates a dark mode for every website you visit, and Search by Image, an add-on that lets you reverse search for photos.
To activate the extensions, make sure you're using the current Nightly version of the browser (200414 12:39), head to settings, and tap "Add-ons" — on that page, you can choose which you want to use. You can also adjust options for individual extensions there.
The latest Nightly release with the extensions is rolling out on the Play Store, but if it's not available to you yet, you can also grab it from APK Mirror. The update will also be available on the regular Preview channel "within the next 2 weeks." Over the next few months, Mozilla will be working hard on adding other add-ons from its recommended extensions program to the browser, so we will hopefully see an even more complete package once the browser goes stable.