Build kinda webapp with Firefox

Firefox removed the SSB feature, so we're not able to add a webapp in this way. I took the script from here and modified it a little bit. The ssb part is removed and I added the part below, so we hide the tabs toolbar and navbar. There is also the option of starting the session in kioskmode, but I wasn't able to copy and paste there. That's why I went this way.
For now you're able to browse trough the internet with one tab. I didn't managed it to block all domains except the given one. If you got any idea how to do that, let me know!

To add a webapp with launcher on your homescreen run it like this:
./add-webapp.sh "Hydrogen" "https://hydrogen.datenkastl.de"

After that you have a new launcher on your homescreen from where you can open the given website inside a new profile.
Have fun!