Add addons via cli

Hello,

I have raspberry pi B+ (not 2 or 3) and I am running that with Rasplex which is based on Libreelec. I am not asking this questions on Rasplex forums because the project has been terminated 2 years ago.

What I would like to do is, install the librespot addons to Rasplex but Rasplex is not supporting to add any addons. also CLI in Rasplex is not allowing me to do anything, like Libreelec

You may ask why I am not installing the LibreElec and install add-ons to run Plex client, it has two reason

1- Raspberry Pi is already suffering performance of Libreelec, Rasplex is not that bad. I believe that it is a little bit lightweight.

2- I have the Hifiberry module on the Raspberry Pi and it is connected to a good pair of a speaker furthermore I want to stream music when the tv is off.

Is there any way to add any Libreelec addons via CLI? I believe that if it is possible on Libreelec, it will work for the Rasplex too.

Thanks.

But as far as I know when I click the install from zip button it shoul run something on the background :)But I coulnt find any document that related with.

Is there any way to unlock the "apt-get" command in Libreelec?

thanks for the info.