I bought it new and didn't use it for years, but recently I have been using it for the past week to run ZeroClaw (a Rust version of OpenClaw AI agent) with a USB 3.0 boot SSD and it works great on USB C power at least 15W (3A@5V). Usually you boot off a 32GB FAT32 Micro SD card, but they get hot and slow down. You can also use a 400mb/s USB 3 all-metal thumb drive. It has 4GB Of RAM you can use it for OpenClaw, but OpenAI bought OpenClaw and they stole all the RAM so f them.
This Pi 4 has a really nice metal case. that has a magnetic cover that comes off to reveal the GPIO pins, and is an excellent passive cooler.
The Pi 4 is what you want for that Software Defined Radio CaribouLite RPi HAT because it won't work with Pi 5; I'm making my own SDR hat. I have switched to BeagleY-AI, which has PoE. I have a good Xeon W-2135 system for sale to run local LLM on but it needs more RAM or a GPU. I have two 8GB GTX 1080 GPUs for $200 that would work well.
I have a lot of good cheap mechanical keyboards, mice, webcams, mics, video lights, live streaming gear, and USB hubs I need to sell to pay the RAM tax due to the sky high price of RAM.