I use ansible on one of my side projects; I use puppet at work. It’s the same reason I use raw docker and not rancher+rke2… it’s not about learning the abstractions; it’s about learning the fundamentals. If I wanted a simple abstraction I’d have deployed truenas and Linuxsserver containers instead of Taco Bell programming everything myself.
There’s nothing preventing you from forking a Lemmy client or server to prototype this. Depending on how you implement the activitypub backend, you might be able to make it transparent to a user if you present an algorithm as an array of cross posts via a /c/ of a server.
Anything more might require forking a client, which might be easier to implement but may be harder to convince a large userbase to migrate to.