It used to let you all extenstions, before mozilla went full google and crippled it.

Firefox Nightly allows you to set whichever set of extensions you desire as the "blessed" extension collection, so you can also create a custom collection and choose that.

But the Firefox rewrite isn’t handling all extensions well.

Container Tabs break hilariously, spawning tenthousands of tabs.

Tampermonkey and similar extensions that spawn popup windows or custom tabs fail, too.

Sidebar extensions like vertical tabs break as well.

But you can get them to work :)

Google Play changed their policies to disallow downloading and executing code from sources other than the Play Store. The blessed extensions in Firefox for Android are actually shipped in the APK.

False. When they rolled this out i was trvially able to replace the allowed extensions id's with a root shell and they downloaded and worked just fine. Also, a website is also downloading and execing js, the same as an extension.

There are other browsers that allow custom extensions, and Firefox Nightly does with a bit of finagling.

'Firefox Klar' literally includes an adblocker