Yeah I do similar, I actually use musicolet to listen to my offline music library (https://krosbits.in/musicolet), an android app that is just offline, no ads, no network permission at all, nothing. It does the job very well and it does not mine any data or show any ads. I highly recommend to give it a try (I assume you use android?).
And to add, while it is free and I could have continued just fine not paying anything to use it, I have paid for the "pro features" that I did not even need (apart from chromecast which I do not use, the other pro features were mainly aesthetic) just to support the developer for providing such a great app that respects my privacy and does not bloat my phone. People think that somehow those who do not want to pay to youtube just want to get everything for free. I have no issue with paying for any service that adds value to my life and respects my privacy, but youtube/google is not just that, and the fact that I use youtube for free does not mean that I would use it the same way if I had to pay for it or had to watch ads all the time. And to be honest, the fact that the app did not require me to support it in order to not send me ads or whatever, made me more incentivised to actually support it, because the incentive to support comes exactly from the appreciation of the experience it provides.
Maybe this sounds like an ad for that app, and it actually is so. I think that such pieces of software that really respect the privacy and provide an alternative to shameless streaming services like the one discussed here are worth being advertised by their happy users.
And to add, while it is free and I could have continued just fine not paying anything to use it, I have paid for the "pro features" that I did not even need (apart from chromecast which I do not use, the other pro features were mainly aesthetic) just to support the developer for providing such a great app that respects my privacy and does not bloat my phone. People think that somehow those who do not want to pay to youtube just want to get everything for free. I have no issue with paying for any service that adds value to my life and respects my privacy, but youtube/google is not just that, and the fact that I use youtube for free does not mean that I would use it the same way if I had to pay for it or had to watch ads all the time. And to be honest, the fact that the app did not require me to support it in order to not send me ads or whatever, made me more incentivised to actually support it, because the incentive to support comes exactly from the appreciation of the experience it provides.
Maybe this sounds like an ad for that app, and it actually is so. I think that such pieces of software that really respect the privacy and provide an alternative to shameless streaming services like the one discussed here are worth being advertised by their happy users.