A pi is quite good, if you only need a nostr relay I guess...

But if you also consider to run a Bitcoin/Lightning node (which I certainly would recommend) Umbrel hardware is superior to a Pi, which is less user friendly to maintain (also depending on your technical skills).

For backing up your nostr activity, Umbrel Home has an app for that https://apps.umbrel.com/app/nostr-relay

I found the Pi to be less stable over time (external SD cards sync can brake down, and be a pain in the ass to recover when updating the Pi).

A start 9 is even better, but more expensive and probably too heavy for this single usecase.

Any further suggestions nostr:nprofile1qqst2yn6pr8nxctzwjqq5su83qdflx8qfwwrwytwjt09y5zfsc6uggspp4mhxue69uhkummn9ekx7mqpremhxue69uhkummnw3ez6un9d3shjtnyv4ex26mjdaehxtndv5q3jamnwvaz7tmwdaehgu3wd3hxy6t5vdhkjm3wvdar5l5kc2x?