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 :)