Wolf Launcher still works on fire tv. The key to using it is the app Launch on Boot as a replacement for Launch Manager (which should be uninstalled). Move Wolf Launcher to front on home page, activate Launch on Boot, once in Wolf you’ll stay there unless you hit the “home” button or the settings function. When you exit an app on Wolf using the back button, you go right back to your Wolf app screen. Instruction for both apps are plentiful on YouTube. Unfortunately, Launch on Boot is not included in RAI at this date but is readily available if you look. Give Wolf another chance, it’s still the best!
Troy just added Launch on Boot to RAI, and reports he’s making a video on this subject
Thanks Troy, you da man
Video will be available on YouTube in the morning. Will leave a link to it here. Thanks @BigDave