The short answer
For a self-hosted mini PC, the best accessories are not flashy. Start with a reliable USB installer, external backup storage, short Ethernet cables, labels, a UPS, and a small cable-management kit. Add a USB 2.5GbE adapter only if the built-in NIC is the real bottleneck.
Useful accessory tiers
| Tier | Buy first | Good fit | Watch out for |
|---|---|---|---|
| Recovery | USB flash drive, spare keyboard, HDMI adapter | Fresh installs and emergency console access | Do not rely on the only USB stick in the house |
| Operations | External backup drive, labels, short patch cables | Routine maintenance and cleaner troubleshooting | Cheap unlabeled cables waste real time later |
| Upgrade | 2.5GbE adapter, small UPS, NVMe enclosure | Faster NAS traffic, graceful shutdowns, migrations | USB NIC chipsets and heat vary by model |
What matters most
- Install media: Keep a labeled USB installer for Proxmox or Debian.
- Backup target: External storage beats no backup, even before a NAS exists.
- Networking: Short known-good cables reduce mystery troubleshooting.
- Power: A small UPS is more useful than one more tiny compute box.
- Documentation: Labels and a one-page service inventory age surprisingly well.
What I would buy first
I would buy two USB flash drives, a short pack of Cat6 patch cables, a label maker or cable labels, and an external USB drive for backups. If the mini PC will run anything important, the next purchase is a UPS.
Source checks
This accessory guide is category guidance. For UPS and backup-specific decisions, use the dedicated LabStack Advisor UPS and backup guides, then check current compatibility notes for any USB NIC, NVMe enclosure, or mini PC model before buying.
Related references: UPS guide, backup strategy guide, and 2.5GbE switch guide.