I don't think your setup will ever be family friendly. I would buy a decent soundbar and let them use that with the TV - especially if you can find one with smart features...
Recently, I bought a Roku Streambar for the TV in the bedroom which is an old LG 32" FHD, with no ARC (so I had to connect the sound bar using HDMI and optical). The Streambar works very well and sounds quite decent for it's size (it's only 14" wide). I have mounted the Streambar to the bottom of the TV (which is mounted on the wall).
Being a Roku device, it has a lot of smart features built-in...
For TV, I use the HDHomeRun app (I have a terrestrial TV HDHomeRun box in the attic) plus the various on-demand players for the UK (BBC iPlayer, etc.)
For streaming, I use Netflix, Amazon and Spotify apps.
For local content, I use the Plex app.
Everything (incl. TV) is controlled from the Roku voice remote. I paid £60 ($75) for the Roku Streambar