I like to work to classic video game soundtracks. Streaming services are garbage for those, but YT is pretty good. You have to play whack a mole with copyright strikes, but somebody will upload most things. It's also the best way to listen to actual game music (the music designed to help you focus) as opposed to orchestral remasters, remixes, homages, etc.

RIP my most recent favorite Zelda background music vid.

I may have noticed that there are small holes, I suppose most of the things if they became unavailable I wouldn't notice as I practice the one big playlist method.