If you can actually figure out some more shit there, document it, that would be extremely useful information, imo.
Theoretically, at least a modified version of lemmy should be constructible within I2P land... but trying to make it accessible via clearnet would... almost certainly be basically not worth it, and arguably defeat the entire point?
It is possible to use I2P as effectively an extremely complex VPN sort of thing for clearnet, via outproxies, but you then just have to trust the outproxy, basically.