But I expect that most addons won’t work out-of-the-box on release day. Many of them will be either conceptionally incompatible or too resource intensive for most Android phones, which makes Android kill the app. The Devs said they created a framework to fix this issue, which extension devs can use to adapt their extensions for mobile browsers.
Don’t expect every single addon to work right away. It’ll take time - probably a year or so - until most relevant extensions support mobile Firefox.