Imo if you’re going to be the only one who would use the instance it is not worth it. Instead look for an instance that lines up with your personal interests (maybe check out the db0 instance).
Content federation basically works on a subscription model so you will only see content from other instances if someonen your instance went out of their way to subscribe to it. Smaller instances suffer under this as they might not even see popular communities from other instances.
Imo the other problem is even if you do decide to buy the manga in today’s world nothing guarantees your possession of what you just bought. DRM and “only readable in publisher app” are the norm rather than the exception which creates a clusterfuck of a mosaic if you want to legally read the manga that are available that way. Comparatively MangaDex is a single centralised experience that is relatively complete.
“We think there is a fundamental misconception about piracy. Piracy is almost always a service problem and not a pricing problem” (Gabe Newell ~2011)