I run a Raspberry Pi 5 that stores files uploaded via web API. I want a removable micro-SD card so a user can pull the card, and use it with any computer. I’m comfortable in Linux and have expert front-and back-end skills, but I’d like a specialist’s view on the best approach for this. • Choosing a cross-platform file system the Pi and common desktop OSs recognize without drivers. • Automating mounts, write-through or real-time sync so files are closed and the card can be removed without corruption. • Performance tuning on the Pi 5 SD bus and ways to avoid wearing out the card. • Fallback ideas—USB-C readers, overlay filesystems, or lightweight daemons that watch the media directory. Deliverables • A concise technical plan (commands, systemd unit, or sample script) that mirrors new media to the card instantly. • A short write-up or call walking me through the trade-offs so I can integrate the solution myself. • Optional proof-of-concept in Bash or Python to demonstrate the workflow. No UI work needed—just expert guidance and a minimal prototype so I can roll the solution into my existing application.