It's super easy...if you have a suitable chromakey backdrop and decent lighting on it. What I'd love is a plugin that replicates (or at least approximates) some of the "virtual chromakey" features of Zoom et al.
I don't currently have access to a good chromakey backdrop and it really is much easier to do it well with a bright green matte screen behind you.
It ain't important, but it would sure be nice!