I'm using a Pi to host a node on Threshold. The project is for a decentralized wrapped Bitcoin on Ethereum, and other chains. I know I'll need a case, heat sink, and probably a few other add ons. There's a ton of different add ons available for the Pi, and I don't know which brands are any good. The machine will be running mostly headless. I might connect with a serial cable on occasion.

Which Pi add ons are recommended for keeping a system running 24/7 and performing well? Not really sure what the load is like running a Pre node for Threshold. Are there any hats that improve the performance of the Pi?

I just know I'll definitely be running Gentoo, and tweaking the OS for a minimal install.

Any Pi will run 24/7 reliably. You should probably buy a Pi 4 with sufficient memory (max. is 8 Gb), with an official keyboard, official case, and official power supply.

Yous shouldn't need a heatsink, but almost any of the heatsink kits would do. If you are worried about heat and 4 Gb is sufficient then you can get a Pi 400 which has a large heatsink under the keyboard.

There are no hats that would improve the performance.

If you are concerned, you could add an off-the-shelf office UPS to keep things running if you ever get a power outage.

Oh no, not again.