Just be thoughtful. Accessibility is not seen as an excuse for breaking copyright. Take precautions.
Also if you’ve never done audio editing I’ll mention audacity the editor has a tool called “auto duck” that’s perfect for lowering the volume of other tracks in a mix when your select track with your voiceover makes noise To enhance clarity of it.
If you just don’t like ads AppleTV works great.
That said if you’re set on something less locked down you might look into Dune-HD boxes. They have some that have a dual OS. One is Android TV (not sure how mod-able) the other is Linux that can have other kinds of apps. They’re virtualized and accessible without a reboot. They have great codec support. Just realize only some of their models have the Android TV dual system thing.