One small but important correction to the OP
the correct path to the autostart file is
/storage/.config/autostart.sh
not
/storage/.kodi/autostart.sh as indicated in OP
There are also some other issues that may occur at startup and I have seen them in LE11.x and current version of this script as of this writing.
1) That issue is that the IPTV Client may try to access the playlist at http://127.0.0.1:8183/playlist.m3u8 before the "FrndlyTV for Channels" web server script is actually ready
2) There is no #EXTM3U header at the beginning of the file at http://127.0.0.1:8183/playlist.m3u8
So on the Libreelec box with the aforementioned script running via ssh we can download the playlist using wget into the .kodi directory thereby creating a static version of this file as it does not change anyway, unless the IP of the machine changes. I therefore recommend a fixed IP address.
cd /storage/.kodi
wget http://127.0.0.1:8183/playlist.m3u8
nano playlist.m3u8
#EXTM3U
at the very top of the file if the file does not start with
add if at the beginning of the file you see
x-tvg-url="xxx","yyy","zzz"
where xxx , yyy and zzz are Guide URLs.
you may (or may not) have to remove these entries as well. I do believe they will work with IPTV merge and the guides will be picked up but they may get in the way of other software
Lastly IPTV Simple Client needs to get pointed to the local playlist file
/storage/.kodi/playlist.m3u8