That comes down to the ask to your audience. You can ask your audience to contribute milk back as value, but I doubt many people will do it. Similarly you can ask them to only contribute BTC, but only very few people have BTC and many are hodling it during the ATH. I think it's better to ask them to contribute BTC, fiat, and whatever else you find valuable for your music or podcast. Ultimately, it's up to you to decide what to ask your audience to contribute back in value.