<p>This is a follow up question for <a href="https://3dprinting.stackexchange.com/q/20196/20803">What are viable substitutes for Raspberry Pi to run Octoprint or similar software for Prusa i3 MK3S+?</a></p>
<p>I was able to grab Raspberry Pi 400 for around $70, so <a href="https://www.raspberrypi.com/news/raspberry-pi-400-the-70-desktop-pc/" rel="nofollow noreferrer">at MSRP</a>, and about half of the current pi 4b prices nowadays. Good deal given shortages, so I ordered it when it was available, and only now I started to think if I can really use it.</p>
<p>Thus, are there any special challenges to using Raspberry Pi 400 as OctoPrint server, and does it have any benefits over regular Pi 4B? Is there any ready-made manual about it I could use?</p>

The recommended hardware for OctoPi is
listed
as:
Recommended hardware: Raspberry Pi 3B, 3B+, 4B or Zero 2. Expect print artifacts and long loading times with other options, especially when adding a webcam or installing third-party plugins.
Now if we compare the specification of the two Pi units:
Raspberry Pi
Processor
RAM
400
BCM2711 quad-core Cortex-A72 @ 1.8GHz
4GB LPDDR4-3200
4B
BCM2711 quad-core Cortex-A72 @ 1.5GHz
1GB, 2GB, 4GB, 8GB LPDDR4-3200
So they are very close in capabilities. The 4B has a slightly slower processor but does have the ability to have more RAM. The 400 does come with a keyboard but its feasibility would depend on your usage (probably not much for OctoPi).
Given the slight disparity in specs, the Raspberry Pi 400 should work fine for OctoPi.