Ok someone has mentioned Logitech Media Player. There is Raspotify too.
Both of these options are Pi compatible and I run both myself.
So here's the use cases for me:
LMS or Squeezebox is a full blown audio media server. I have pulled the music off and old iPod and put it on a server that LMS can "see" and I can play via speakers and Bluetooth.
There's plugins for LMS and Spotify is one of them. Another that I use is the Chromecast Bridge that allows LMS to connect to Google devices. There's an Apple Bridge, a UPNP bridge and a DLNA bridge too. Meaning you can connect all sorts of shit to this server and play your own music, Tidal, Spotify, SoundCloud, YouTube, etc.
It's far more involved in it's set up but if you have a pi lying around it's a great option.
Raspotify is also known as Spotify Connect. You can install this in Home Assistant but your HA device will need speakers. You can also install it on any pi and it just shows up as a connection in Spotify.
I see you're talking about a tablet you have. I run Fully Kiosk on a tablet myself and recently noticed that it shows in HA as a media player. I haven't tried to play media through it yet but maybe a quick and easy option for you.
Edit: I just tried using the Fully Kiosk Browser media player on my tablet and it worked just fine. No idea how to get Spotify in there but there you go.