Instalamos docker y paquetes necesarios

sudo apt-get install -f software-properties-common
sudo su -
add-apt-repository universe
apt-get update
apt-get install -y apparmor-utils apt-transport-https avahi-daemon ca-certificates curl dbus jq network-manager socat software-properties-common
curl -sSL https://get.docker.com | sh

Ahora instalamos home assistant del repositorio de github

Repositorio: https://github.com/home-assistant/supervised-installer

Comandos para instalar:

curl -Lo installer.sh https://raw.githubusercontent.com/home-assistant/supervised-installer/master/installer.sh
bash installer.sh --machine raspberrypi4

https://www.home-assistant.io/integrations/spotify/

En Developer Tools, seleccionamos SERVICES y ponemos:

Service: media_player.play_media

En el desplegable seleccionamos:

Entity: media_player.spotify_joselegido

entity_id: media_player.spotify_joselegido
media_content_id: https://open.spotify.com/playlist/4kPUSDh6ELg2QX251qM6zi?si=cEt1dw6mRYiulWN4uj9o4w
media_content_type: playlist

Developer Tools > Services

Service:

media_player.play_media

Service Data (YAML, optional):

entity_id: media_player.google_home
media_content_id: 'https://mediavod-lvlt.rtve.es/resources/TE_SHETACA/mp3/0/6/1613119445760.mp3'
media_content_type: audio/mp3

Con fichero local. El fichero está en:
Raspberry:

/usr/share/hassio/media

Docker:

/media

En configuration.yml (creo que no es necesario)

docker exec -ti homeassistant bash

homeassistant:
  media_dirs:
    local: /media

entity_id: media_player.google_home
media_content_id: "media-source://media_source/local/viernes.mp3"
media_content_type: audio/mp3