This requires nothing except a webcam and a willingness to install an app to act as a virtual webcam for you. Both options here can be tested for free, and they both display a very noticeable watermark when you do so.
But they both give you Zoom’s standard background features (automatic background detection (with or without a green-screen), replacement with a static image or a video file) and the very nice “blur the background” feature.
XSplit VCam can be paid for for a single month for $6, three months for $10 (lots of NaNo time!), or lifetime for $50. So, for just November, it’s about the cost of a fancy coffee that we’re not going to coffee shops to get. Unfortunately, it’s Windows only (sorry, Mac folks!)
Personify’s ChromaCam is $30 lifetime, has the same features, and does both Windows and Mac.
My desktop is not powerful enough to do automatic background detection in Zoom (but it does do motion backgrounds and greenscreen). However, both XSplit VCam and ChromaCam can do automatic background extraction on my older CPU. (And they’re free, so you can try it first.)
(I haven’t tested on the Mac, though.)
Upside: easy to set up, it just uses your webcam normally, and creates a new virtual camera you can use in discord (or skype, or teams, or meetings, or even zoom).
Downside: annoying watermark, which costs $ to get rid of.
They only work with prerecorded videos (like Zoom). You can always use OpenShot to build your own video backgrounds.
BUT. You can also use the automatic background extraction, a replacement background using an all green image like this one, and feed it into OBS Studio as a webcam, throw on a chromakey filter just like all the OBS Studio options do, and then do all the fun OBS tricks.