It's a bit more bulky (classic iPod sized), but check out Tangara: <https://www.crowdsupply.com/cool-tech-zone/tangara>. Stock, easily replaceable parts, USB-C+3.5mm+BT, SDXC slot with 2TB limit, standard lipo battery, OSS & hackable firmware that's difficult to brick, basically every bit of it is designed to last decades.