How to install e.g. omxplayer on hassio?

Hi,
I’m looking for some guidance or tips on the following issue:
I need to play a sound when a sensor is triggered. I found several posts about this topic but I can’t seem to install omxplayer
I want to use the on-board audio of the Raspberry Pi that runs my home-assistant
My installation is self-contained configuration which I downloaded and expanded to an SD card. It includes the OS and hassio.
I can ssh into hassio. I think I end up inside a docker container
My questions:

  1. can anyone explain how I can install software (apt-get seems not present)
  2. given that we are inside a container, would it be possible to address the audio hardware and play a sound?
    PS: I am not very familiar with home-assistant (yet). Let me know if I missed some important information.
    thanks,
    chrisV
  1. You can’t

However, you (or somebody else) could create an add-on for omxplayer.