[Fire HD 8 and HD 10 Android Development] vjunk:
I received almost the exact error you did except my first traceback line said File ".pyarmor/pack/dist/Popup.py", line 2, in <module>. It was due to missing dependencies. In my case, the first one I was missing was python3-pip. At first, I didn't see the message to install Pip because it disappears from the screen too fast, but I finally caught it after a few times. I installed it with sudo apt install python3-pip (Ubuntu/Debian-based distros). Installing it got me to the screen that, if I recall, checks for dependencies and it showed I was missing the bottom two. So I installed three more packages, although one of them may have installed one of the others automatically if I didn't. In all, here are the packages I was missing:

python3-pip
python3-tk
python3-pil
python3-pil.imagetk

@Datastream33, here are the other items I noticed with the Linux Fire Toolbox:

Custom Launcher: selected Microsoft Launcher. It installed, but I got "Failed to install Automate due to an error:" with no error shown. I installed Automate manually and was able to proceed, except that I could no longer see the Home button. (See below for details.)

Google: same issue as others, which I believe is fixed now.

Hybrid Apps: installed OK, but had the Fire Toolbox partially covered so didn't see that it was done. Just saw "Installing Netflix..." and started wondering why it was taking so long. Perhaps remove "Installing Netflix..." when it's done?

Keyboard & Input: installing a custom keyboard broke the Fire Standard Keyboard. Reinstalling it brought the selections back in Settings, but when one of them was selected, no keyboard comes up.

Modify System Settings: I connect to more than one Wi-Fi network so went through the process for each network. May want to include a note about that, unless you did and I missed it!

(Second Page of Tools): didn't realize that there was a second page until I stumbled across it accidentally. May want to make it more obvious.

More on Microsoft Launcher. After installing Automate manually, I was able to complete the steps, but the replacement Home button was not showing up. However, it still worked if I tapped where it should have been. After reading through this thread, I thought it may have to do with choosing the wide nav button layout so I reset the nav bar with settings delete secure sysui_nav_bar, then tried to run the Custom Launcher process again. However, this time it just verified that the Microsoft Launcher and Automate were installed and skipped the rest of the steps. Thinking that Fire Toolbox may be detecting that Microsoft Launcher and Automate are installed and skipping the rest of the steps because of that, I uninstalled them, then reran Custom Launcher, which re-installed Microsoft Launcher. I reinstalled Automate again and ran Custom Launcher again, but it still skipped the rest of the steps. I happened to find the flow file on the tablet so imported it, but the home button still isn't bringing up Microsoft Launcher. Also tried it with Nova Launcher. Searching through this thread again today, I found a post listing the required permissions for Automate. I will check that, but if it still doesn't work, can you let me know how to "reset" Custom Launcher so it runs all of the steps again? It would also help to have that ability in the Fire Toolbox (like I think the Windows version has).