Two Pi 3Bs and an old Pi 2 in a drawer — what still runs genuinely well on 1GB in 2026?

Be aware of the hardware ceiling before you pick: on a Pi 3 the ethernet port hangs off the same USB 2 bus as the storage, so realistic throughput once you are also reading from a USB drive is well under 100Mbit. That rules out file server, media transcoding and anything backup-shaped where you care about the speed. It does not rule out anything that moves small amounts of data, which is most of the genuinely useful stuff.

Things that have run for years on my Pi 3s without complaint: network-wide DNS filtering, a print and scan server so the ancient printer becomes wireless, an ADS-B receiver feeding flight data with a cheap USB dongle, and a Syncthing node that keeps a copy of the family photos in a different room. All of those are I/O light and RAM light, which is exactly what a 1GB board wants. The Pi 2 I would use as the sacrificial test box you break things on.

I tried to make a Pi 3 into a media server for the TV and it was miserable — direct play was fine, anything needing a transcode fell over, and I spent two weekends tuning it before admitting the board could not do the job. That is the one category I would tell you to skip outright. Everything else on the list here I have had working with zero drama.

Sensor logging is where an old Pi is still perfect and a new one is a waste. Temperature and humidity in the loft, a water sensor by the washing machine, a door contact, all writing to a tiny database and drawing one graph. Small, boring, runs for years, and you actually look at it when something floods.